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Common Core Math2nd GradeNumbers in Base Ten

2.NBT.5: Add and Subtract Within 100 Fluently

Also written as 2.NBT.B.5 and CCSS.MATH.CONTENT.2.NBT.B.5 · Cluster: Use place value understanding and properties of operations to add and subtract.

Make a 2.NBT.5 WorksheetAll 26 2nd Grade Math Standards

The Official Wording

Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.

Common Core State Standards, Grade 2, Number & Operations in Base Ten · Read it at the source · Checked October 14, 2026

What 2.NBT.5 Means in Plain English

Second graders add and subtract any two numbers within 100, like 47 + 38 or 83 − 47, with strategies they can explain: split into tens and ones, jump by tens along a number line, or count up from 47 to 83 because subtraction is a missing addend.

Fluent means quick and accurate with a method that makes sense, not a memorized column procedure. The written algorithm is not required until 4th grade (4.NBT.4). The same place-value moves stretch to 1,000 with models next (2.NBT.7), and 3rd grade expects fluency there too (3.NBT.2).

2.NBT.5 I Can Statements

  • I can add two numbers within 100 by splitting them into tens and ones.
  • I can subtract within 100 by counting up to the bigger number.
  • I can explain the strategy I used and why it works.

2.NBT.5 Worked Example

One addition and one subtraction built from the same three numbers, so the link between the two operations is right there.

Problem

Add 47 + 38, then subtract 83 − 47.

47 + 38 by place value, then 83 − 47 by adding up
  1. Split both numbers into tens and ones, and add the tens first.40 + 30 = 70
  2. Add the ones. 7 + 8 is 15, a ten and five ones.7 + 8 = 15
  3. Put the parts together: 70 and 15 is 85.70 + 15 = 85
  4. For 83 − 47, think addition: 47 and how much more makes 83? Jump to the next ten, then on to 83.47 + 3 = 50, 50 + 33 = 83
  5. The jumps add up to the difference.3 + 33 = 36, so 83 − 47 = 36
Answer47 + 38 = 85 and 83 − 47 = 36

Check it: Subtraction undoes addition, so 36 + 47 should give 83: 30 + 40 = 70, 6 + 7 = 13, 70 + 13 = 83. It does.

Common Mistakes with 2.NBT.5

Losing the regrouped ten

47 + 38 = 75, with 7 + 8 written as 5

Try this: Add the tens first, then the ones, then combine: 70 and 15 is 85. The 15 cannot shrink to a 5.

Smaller digit from bigger, whatever the order

83 − 47 = 44, from 7 − 3 = 4 and 8 − 4 = 4

Try this: Count up from 47 to 83 on an open number line instead: 3 to reach 50, then 33 more. The difference is 36.

Counting by ones for everything

Adds 38 to 47 with 38 tally marks, and gets 84 after a slip

Try this: Teach jumps of ten on a number line: 47, 57, 67, 77, then 8 more. Fewer steps means fewer places to slip.

Where 2.NBT.5 Fits

Comes Before1.NBT.4Add within 100, including a two-digit number and a multiple of ten.1.NBT.6Subtract multiples of 10 from multiples of 10 within 90.2.OA.2Facts within 20, which every tens-and-ones step uses.
Alongside2.OA.1Word problems within 100 that need these sums and differences.2.NBT.6Add up to four two-digit numbers.2.NBT.9Explain why the strategy works.
Comes Next2.NBT.7Add and subtract within 1,000 with models and drawings.3.NBT.2Fluently add and subtract within 1,000.4.NBT.4Add and subtract multi-digit numbers with the standard algorithm.

Practice 2.NBT.5

Addition Worksheet GeneratorFree ToolTwo-digit sums like 47 + 38, with or without regrouping. Students show the tens-and-ones split beside each one.Two-digitWith regroupingAnswer key
Make a Worksheet
Subtraction Worksheet GeneratorFree ToolDifferences within 100 like 83 − 47. Ask for an open number line under each problem, counting up from the smaller number.Two-digitWith regroupingAnswer key
Make a Worksheet

Quick Check

  1. What is 56 + 27? Show the tens and ones.
  2. What is 91 − 46?
  3. Tomas has 64 baseball cards. He gets 29 more. How many does he have now?

2.NBT.5: Other Names

2.NBT.52.NBT.B.5CCSS.MATH.CONTENT.2.NBT.B.5

Common Core State Standards © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved. Official wording from the Common Core State Standards PDFs at corestandards.org, last checked October 14, 2026. The explanation, I can statements, example, mistakes and practice on this page are EMStudio’s own, written beside the official wording. They are not part of the standard.