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Common Core Math1st GradeNumbers in Base Ten

1.NBT.5: Find 10 More or 10 Less

Also written as 1.NBT.C.5 and CCSS.MATH.CONTENT.1.NBT.C.5 · Cluster: Use place value understanding and properties of operations to add and subtract.

Get the Hundreds ChartAll 21 1st Grade Math Standards

The Official Wording

Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

Common Core State Standards, Grade 1, Number & Operations in Base Ten · Read it at the source · Checked October 14, 2026

What 1.NBT.5 Means in Plain English

First graders find 10 more or 10 less than a two-digit number in their head. For 64 they say 74 and 54 straight away, because only the tens digit moves, and they explain it: one more ten, or one ten fewer, and the ones stay put.

A child who counts 65, 66, 67 up to 74 has not got the idea yet. A hundreds chart helps first, then goes away. In 2nd grade the same move works with 100 more and 100 less within 1,000 (2.NBT.8).

1.NBT.5 I Can Statements

  • I can find 10 more than a number without counting.
  • I can find 10 less than a number without counting.
  • I can explain why only the tens digit changes.

1.NBT.5 Worked Example

Both directions from one number, with the explanation a 1st grader gives instead of a count.

Problem

Find 10 more and 10 less than 64, without counting, and explain how you know.

Only the tens move
  1. Read 64 as tens and ones.64 = 6 tens and 4 ones
  2. Ten more means one more ten. The ones do not change.7 tens and 4 ones
  3. Read it back as a number.64 + 10 = 74
  4. Ten less means one ten fewer. The 4 ones still stay.5 tens and 4 ones, so 64 - 10 = 54
  5. Explain it without counting: only the tens digit moved, up one or down one.54, 64, 74
Answer10 more than 64 is 74, and 10 less is 54

Check it: On a hundreds chart, 74 sits right below 64 and 54 right above it. One row is ten squares.

Common Mistakes with 1.NBT.5

Counting by ones to get there

Says “65, 66, 67 ...” all the way to 74

Try this: Hide the hundreds chart, ask for 10 more than 64, and ask which digit changes before any counting starts.

Changing the ones digit

10 more than 64 is 65

Try this: Build 64 with rods and cubes, add one rod, and point out that the loose cubes did not move at all.

Stuck when the tens run out

10 less than 17 answered “you can’t”, or written as 07

Try this: Show 17 as one rod and 7 cubes, take the rod away, and name what is left: 7 ones, written as 7.

Where 1.NBT.5 Fits

Comes BeforeK.CC.1Count to 100 by ones and by tens.1.NBT.2Know that the tens digit counts bundles of ten.
Alongside1.NBT.4Add a two-digit number and a multiple of 10.1.NBT.6Subtract multiples of 10 within 90.
Comes Next2.NBT.8Mentally add or subtract 10 or 100 to a number from 100 to 900.

Practice 1.NBT.5

Math Worksheet GeneratorFree ToolTen more and ten less tables at the 1st grade level: a column of two-digit numbers, a column for 10 less and a column for 10 more.Grade 110 more, 10 lessAnswer key
Make a Worksheet

Quick Check

  1. What is 10 more than 38?
  2. What is 10 less than 91?
  3. The class has read 45 books. After 10 more, how many will they have read? Explain without counting.

1.NBT.5: Other Names

1.NBT.51.NBT.C.5CCSS.MATH.CONTENT.1.NBT.C.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.