Speedy Subtractions

Speedy Subtractions

Ages 5–7 · 6 minutes · Math

Learn quick techniques for two types of subtraction problems

In this subtraction lesson, students will learn the following two new subtraction techniques:

- Subtracting ten by removing the 1 in the tens place
- Using related doubles addition problems to perform subtraction problems like 12 – 6 and 14 – 7

Part of

Standards alignment

Common Core State Standards

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.NBT.B.2.b — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: the numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • MP8 — Look for and express regularity in repeated reasoning.

Alabama

  • MA19.1.14 — Given a two-digit number, mentally find 10 more or 10 less than the number without having to count, and explain the reasoning used.
  • MA19.1.6 — Add and subtract within 20.
  • MA19.1.4 — Explain subtraction as an unknown-addend problem.
  • MA19.2.2 — Fluently add and subtract within 20 using mental strategies such as counting on, making ten, decomposing a number leading to ten, using the relationship between addition and subtraction, and creating equivalent but easier or known sums.
  • MA19.K.14 — Compose and decompose numbers from 11 to 19 by using concrete objects or drawings to demonstrate understanding that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.

Alaska

  • 1.NBT.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.6 — Add and subtract using numbers up to 20, demonstrating fluency for addition and subtraction up to 10. Use strategies such as • counting on • making ten (8 + 6 = 8 + 2 + 4 = 10 + 4 = 14) • decomposing a number leading to a ten (13 - 4 = 13 - 3 - 1 = 10 - 1 = 9) • using the relationship between addition and subtraction, such as fact families, (8 + 4 = 12 and 12 - 8 = 4) • creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • 1.NBT.2.b — The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight or nine ones.

Arizona

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count.
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem within 20 (e.g., subtract 10 - 8 by finding the number that makes 10 when added to 8).
  • 1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
  • 2.OA.B.2 — Fluently add and subtract within 20. By end of Grade 2, know from memory all sums of two one-digit numbers.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.

Arkansas

  • 1.CAR.2 — Use computational fluency to add and subtract within 20 using manipulatives and/or a variety of strategies.
  • 1.CAR.5 — Demonstrate the relationship between addition and subtraction by solving problems, using an inverse operation.
  • 1.NPV.6 — Use mental strategies to find 10 more or 10 less than a given two-digit number.
  • 1.NPV.3 — Explain the place value of ones and tens in two-digit numbers, using concrete models, diagrams, numbers, or words.

California

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • MP7 — Look for and make use of structure.

Colorado

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 − 4 = 13 − 3 − 1 = 10 − 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 − 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 − 8 by finding the number that makes 10 when added to 8.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (such as 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.

Connecticut

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • MP7 — Look for and make use of structure.

Delaware

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • 1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:

Florida

  • MA.1.AR.2.1 — Restate a subtraction problem as a missing addend problem using the relationship between addition and subtraction.
  • MA.1.NSO.2.2 — Add two whole numbers with sums from 0 to 20, and subtract using related facts with procedural reliability.
  • MA.1.NSO.2.3 — Identify the number that is one more, one less, ten more and ten less than a given two-digit number.
  • MA.1.NSO.1.3 — Compose and decompose two-digit numbers in multiple ways using tens and ones. Demonstrate each composition or decomposition with objects, drawings and expressions or equations.
  • MA.K12.MTR.3.1 — Complete tasks with mathematical fluency. Mathematicians who complete tasks with mathematical fluency: • Select efficient and appropriate methods for solving problems within the given context. • Maintain flexibility and accuracy while performing procedures and mental calculations. • Complete tasks accurately and with confidence. • Adapt procedures to apply them to a new context. • Use feedback to improve efficiency when performing calculations.

Georgia

  • 1.NR.2.1 — Use a variety of strategies to solve addition and subtraction problems within 20.
  • 1.NR.2.3 — Recognize the inverse relationship between subtraction and addition within 20 and use this inverse relationship to solve authentic problems.
  • 1.NR.1.2 — Explain that the two digits of a 2-digit number represent the amounts of tens and ones.
  • 1.NR.2.2 — Use pictures, drawings, and equations to develop strategies for addition and subtraction within 20 by exploring strings of related problems.
  • 1.NR.5.2 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

Hawaii

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • MP7 — Look for and make use of structure.

Idaho

  • 1.NBT.C.5 — Given a two-digit number, mentally find ten more or ten less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Demonstrate fluency for addition and subtraction within ten, use strategies to add and subtract within 20.
  • 1.MP8 — Look for and express regularity in repeated reasoning.
  • 1.OA.B.4 — Restate a subtraction problem as a missing addend problem using the relationship between addition and subtraction.
  • K.NBT.A.1 — Compose (put together) and decompose (break apart) numbers from 11 to 19 into ten ones and some further ones, and record each composition or decomposition by using physical, visual, or symbolic representations; understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.

Illinois

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • MP.7 — Look for and make use of structure.

Indiana

  • 1.CA.1 — Demonstrate fluency with addition facts and the corresponding subtraction facts within 20. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a 10 (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13). Model the role of 0 and the equal sign in addition and subtraction using objects or drawings. (E)
  • K.NS.7 — Define and model a "ten" as a group of ten ones. Model equivalent forms of whole numbers from 10 to 20 as groups of tens and ones using objects and drawings. (E)
  • 1.NS.2 — Model place value concepts of two-digit numbers, multiples of 10, and equivalent forms of whole numbers using objects and drawings. (E)
  • PS.7 — Look for and make use of structure.

Iowa

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, using strategies such as: • Counting on. • Making ten (for example, 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14). • Decomposing a number leading to a ten (for example, $13 − 4 = 13 − 3 − 1 = 10 − 1 = 9)$. • Using the relationship between addition and subtraction (for example, knowing that 8 + 4 = 12, one knows 12 − 8 = 4). • Creating equivalent but easier or known sums (for example, adding 6 + 7 by creating the known equivalent $6 + 6 + 1 = 12 + 1 = 13)$. • Counting up to subtract.
  • 1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases.
  • SMP7 — Look for and make use of structure.

Kansas

  • 1.NBT.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.6 — Add and subtract within 20, demonstrating fluency (efficiently, accurately, and flexibly) for addition and subtraction within 10. Use mental strategies such as counting on; making ten (e.g. 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g. 13 − 4 = 13 − 3 − 1 = 10 − 1 = 9); using the relationship between addition and subtraction (e.g. knowing that 8 + 4 = 12, one knows 12 − 8 = 4); and creating equivalent but easier or known sums (e.g. adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 − 8 by finding the number that makes 10 when added to 8.
  • K.NBT.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, (e.g. by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g. 10 + 8 = 18 and 19 = 10 + 9); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.

Kentucky

  • KY.1.NBT.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • KY.1.OA.6.b — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making 10; decomposing a number leading to a 10; using the relationship between addition and subtraction; creating equivalent but easier or known sums.
  • KY.1.OA.6 — Add and subtract within 20.
  • KY.K.NBT.1 — Compose and decompose numbers from 11 to 19 using quantities (numbers with units) of ten ones and some further ones. Understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • KY.1.OA.4 — Understand subtraction as an unknown-addend problem.

Louisiana

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use mental strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • K.NBT.A.1.a — Understand that the numbers 11–19 are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • MP8 — Look for and express regularity in repeated reasoning.

Maine

  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.NBT.B.2b — The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.
  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.

Maryland

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.

Massachusetts

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used. Identify arithmetic patterns of 10 more and 10 less than using strategies based on place value.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use mental strategies such as counting on; making 10 (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a 10 (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.

Michigan

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • MP7 — Look for and make use of structure.

Minnesota

  • 1.1.1.4 — Find a number that is 10 more or 10 less than a given number. For example: Using a hundred grid, find the number that is 10 more than 27.
  • 2.1.2.1 — Use strategies to generate addition and subtraction facts including making tens, fact families, doubles plus or minus one, counting on, counting back, and the commutative and associative properties. Use the relationship between addition and subtraction to generate basic facts. For example: Use the associative property to make tens when adding 5 + 8 = (3 + 2) + 8 = 3 + (2 + 8) = 3 + 10 = 13.
  • 1.1.1.1 — Use place value to describe whole numbers between 10 and 100 in terms of tens and ones. For example: Recognize the numbers 21 to 29 as 2 tens and a particular number of ones.
  • 1.1.2.1 — Use words, pictures, objects, length-based models (connecting cubes), numerals and number lines to model and solve addition and subtraction problems in part-part-total, adding to, taking away from and comparing situations.

Mississippi

  • 1.NBT.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.
  • K.NBT.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones to understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8).
  • MP7 — Look for and make use of structure.

Missouri

  • 1.NBT.B.6 — Calculate 10 more or 10 less than a given number mentally without having to count.
  • 1.RA.C.7 — Add and subtract within 20.
  • 1.NBT.A.2 — Understand two-digit numbers are composed of ten(s) and one(s).
  • 1.NBT.B.7 — Add or subtract a multiple of 10 from another two-digit number, and justify the solution.
  • 1.RA.B.6 — Demonstrate that subtraction can be solved as an unknown-addend problem.

Montana

  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • MP7 — Look for and make use of structure.

Nebraska

  • 1.N.4.a — Add and subtract within 20, using flexible strategies such as counting on or counting back, making ten, using ten, and using doubles and near doubles.
  • 1.N.4.d — Mentally find 10 more or 10 less than a two-digit number without having to count and explain the reasoning used.
  • 1.N.4.g — Subtract multiples of ten from two-digit numbers (positive or zero differences) using concrete models, drawings, and strategies that reflect an understanding of place value, the relationship between addition and subtraction, and the properties of operations. Relate the strategy to a written method and explain the reasoning used to solve.
  • 1.N.5.b — Use the relationship of addition and subtraction to solve subtraction problems (e.g., find 12 – 9 = , using the addition fact 9 + 3 = 12).
  • 1.N.3.a — Understand 10 as a bundle, collection, or (more abstractly) composition of ten ones and that the two digits of a two-digit number represent a composition of some tens and some ones.

Nevada

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • MP7 — Look for and make use of structure.

New Hampshire

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • MP7 — Look for and make use of structure.

New Jersey

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows $12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13$).
  • 1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: a. 10 can be thought of as a bundle of ten ones — called a “ten.” b. The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones. c. The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.

New Mexico

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.

New York

  • NY-1.NBT.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • NY-1.OA.6.a — Add and subtract within 20. Use strategies such as: • counting on; • making ten; • decomposing a number leading to a ten; • using the relationship between addition and subtraction; and • creating equivalent but easier or known sums.
  • NY-1.NBT.2.b — Understand the numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.
  • NY-1.OA.4 — Understand subtraction as an unknown-addend problem within 20.

North Carolina

  • NC.1.NBT.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • NC.1.OA.6 — Add and subtract, within 20, using strategies such as: • Counting on • Making ten • Decomposing a number leading to a ten • Using the relationship between addition and subtraction • Using a number line • Creating equivalent but simpler or known sums
  • NC.1.NBT.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. • Unitize by making a ten from a collection of ten ones. • Model the numbers from 11 to 19 as composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones. • Demonstrate that the numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens, with 0 ones.
  • NC.2.OA.2 — Demonstrate fluency with addition and subtraction, within 20, using mental strategies.

North Dakota

  • 1.NO.NBT.5 — Mentally add or subtract 10 to or from a given two-digit number and explain the reasoning used.
  • 2.AR.OA.1 — Automatically add and subtract within 20.
  • 1.NO.NBT.4 — Subtract multiples of 10 within 100 using concrete models, drawings, and strategies that reflect an understanding of place value.

Ohio

  • 1.NBT.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.6 — Add and subtract within 20, demonstrating fluency with various strategies for addition and subtraction within 10. Strategies may include counting on; making ten, e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14; decomposing a number leading to a ten, e.g., 13 − 4 = 13 − 3 − 1 = 10 − 1 = 9; using the relationship between addition and subtraction, e.g., knowing that 8 + 4 = 12, one knows 12 − 8 = 4; and creating equivalent but easier or known sums, e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13.
  • 1.NBT.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: 10 can be thought of as a bundle of ten ones — called a “ten;” the numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones; and the numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
  • 1.OA.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 − 8 by finding the number that makes 10 when added to 8.

Oklahoma

  • 1.N.1.6 — Find a number that is 10 more or 10 less than a given number up to 100.
  • 2.N.2.1 — Use the relationship between addition and subtraction to generate basic facts with sums and minuends of up to 20.
  • 2.N.2.2 — Demonstrate fluency with basic facts of addition and subtraction with sums and minuends of up to 20.
  • 1.N.1.2 — Use concrete representations to describe whole numbers between 10 and 100 in terms of tens and ones. Know that 10 is equivalent to 10 ones and 100 is equivalent to 10 tens.

Oregon

  • 1.NBT.C.5 — Without having to count, mentally find 10 more or 10 less than a given two-digit number and explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10 with accurate, efficient, and flexible strategies.
  • 1.NBT.B.2 — Understand 10 as a bundle of ten ones and that the two digits of a two-digit number represent amounts of tens and ones.
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem.

Pennsylvania

  • CC.2.2.1.A.1 — Represent and solve problems involving addition and subtraction within 20.
  • CC.2.2.1.A.2 — Understand and apply properties of operations and the relationship between addition and subtraction.
  • CC.2.1.1.B.2 — Use place-value concepts to represent amounts of tens and ones and to compare two digit numbers.
  • CC.2.1.1.B.3 — Use place-value concepts and properties of operations to add and subtract within 100.

Rhode Island

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used. Identify arithmetic patterns of 10 more and 10 less than using strategies based on place value.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use mental strategies such as counting on; making 10 (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a 10 (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.

South Carolina

  • 1.ATO.6a — Demonstrate addition and subtraction through 20.
  • 1.NSBT.5 — Determine the number that is 10 more or 10 less than a given number through 99 and explain the reasoning verbally and with multiple representations, including concrete models.
  • 1.ATO.4 — Understand subtraction as an unknown addend problem.
  • 1.NSBT.2b — Understand place value through 99 by demonstrating that the tens digit in a two-digit number represents the number of tens and the ones digit represents the number of ones.

South Dakota

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.

Tennessee

  • 1.OA.B.4 — Understand the relationship between addition and subtraction by representing subtraction as an unknown-addend problem. For example, to solve 10 – 8 = , a student can use 8 + __ = 10.
  • 1.OA.C.5 — Add and subtract within 20 using strategies such as counting on, counting back, making 10, related known facts, and composing/decomposing numbers with an emphasis on making ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9 or adding 6 + 7 by creating the known equivalent 6 + 4 + 3 = 10 + 3 = 13 OR 6 + 6 + 1 = 12 + 1).
  • 1.NBT.C.6 — Mentally find 10 more or 10 less than a given two-digit number without having to count by ones and explain the reasoning used.
  • 1.OA.C.6 — Use mental strategies flexibly and efficiently to develop fluency in addition and subtraction within 20. By the end of grade 1, know all sums and differences up to 10.
  • 1.NBT.C.7 — Subtract multiples of 10 from any number in the range of 10-99 using concrete models, drawings, strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.

Texas

  • 1.3D — apply basic fact strategies to add and subtract within 20, including making 10 and decomposing a number leading to a 10;
  • 1.5C — use relationships to determine the number that is 10 more and 10 less than a given number up to 120;
  • 1.3E — explain strategies used to solve addition and subtraction problems up to 20 using spoken words, objects, pictorial models, and number sentences; and
  • 1.5F — determine the unknown whole number in an addition or subtraction equation when the unknown may be any one of the three or four terms in the equation; and

Utah

  • 1.NBT.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.6 — Add and subtract within 20.
  • 1.OA.6.a — Use strategies such as counting on; making ten (for example, 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (for example, 13 - 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (for example, knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (for example, adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.NBT.2.b — The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.

Vermont

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.

Virginia

  • 1.CE.1e — Solve addition and subtraction problems within 20 using various strategies (e.g., inverse relationships: if 9 + 3 = 12 then 12 - 3 = 9; decomposition using known sums/differences: 9 + 7 can be thought of as 9 decomposed into 2 and 7, then use doubles, 7 + 7 = 14; 14 + 2 = 16 or decompose the 7 into 1 and 6; make a ten: 1 + 9 = 10; 10 + 6 = 16).
  • 1.CE.1 — The student will recall with automaticity addition and subtraction facts within 10 and represent, solve, and justify solutions to single-step problems, including those in context, using addition and subtraction with whole numbers within 20. Students will demonstrate the following Knowledge and Skills:
  • 2.CE.1d — Demonstrate fluency with addition and subtraction within 20 by applying reasoning strategies (e.g., doubles, near doubles, make-a-ten, compensations, inverse relationships).

Washington

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • MP7 — Look for and make use of structure.

Washington, D.C.

  • 1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
  • K.NBT.A.1 — Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • MP8 — Look for and express regularity in repeated reasoning.

West Virginia

  • M.1.13 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count and explain the reasoning used.
  • M.1.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10 and use strategies such as· counting on; • making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); • decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 -1 = 10 -1 = 9); • using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8= 4); and • creating equivalent but easier or known sums (e.g., adding 6+7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • M.1.10 — Understand the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: a. 10 can be thought of as a bundle of ten ones - called a "ten." (e.g., A group of ten pennies is equivalent to a dime.) b. The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight or nine ones. c. The numbers 10, 20, 30, 40, SO, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight or nine tens (and 0 ones).
  • M.1.4 — Understand subtraction as an unknown-addend problem (e.g., subtract 10 - 8 by finding the number that makes 10 when added to 8).

Wisconsin

  • M.1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
  • M.1.OA.C.6 — Use multiple strategies to add and subtract within 20. a. Flexibly and efficiently add and subtract within 10 using strategies that may include mental images and composing and decomposing up to 10. b. Add and subtract within 20 using objects, drawings, or equations. Use multiple strategies that may include counting on; making a ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
  • M.1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: a. 10 can be thought of as a bundle of ten ones-called a "ten." b. The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones. c. The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
  • M.1.OA.C.5 — Use counting and subitizing strategies to explain addition and subtraction. a. Relate counting to addition and subtraction (e.g., by counting on 2 to add 2). b. Use conceptual subitizing in unstructured arrangements with totals up to 10 and structured arrangements anchored to 5 or 10 (e.g., ten frames, double ten frames, math rack/rekenrek) with totals up to 20 to relate the compositions and decompositions to addition and subtraction.

Wyoming

  • 1.NBT.G.5 — Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used .
  • 1.OA.C.6 — Add and subtract within 20, demonstrating fluency in addition and subtraction within 10. Use strategies such as counting on; making ten using the relationship between addition and subtraction.
  • 1.NBT.F.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
  • 1.OA.B.4 — Understand subtraction as an unknown-addend problem.