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  • 1st Grade
  • Math
  • About 10 minutes

Think Addition

Use an addition fact you know to find the missing number.

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Think AdditionName:Date:Use an addition fact you know to find the missing number.12 − 9 = ? Think: 9 + ? = 12Start at 9 and count up to 12: 10, 11, 12. That is 3 more!So 12 − 9 = 3.12−6=Think:6+=1216−7=Think:7+=1618−9=Think:9+=1813−9=Think:9+=1316−6=Think:6+=1612−9=Think:9+=1213−8=Think:8+=1315−7=Think:7+=15k5printables.com · Sheet #11924601 · Aligned with Common Core 1.OA.C.6

This is sheet #11924601.

How to do it

  1. Read the take-away problem.
  2. Start at the small number. Count up to the big one.
  3. How many did you count? That is the answer.

Teaching tip

For 12 - 9, counting up from 9 is just 3 hops: 10, 11, 12. This sheet is aligned with Common Core 1.OA.C.6.

Think Addition worksheet for 1st grade (subtraction within 20), free printable
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About this worksheet

Each subtraction fact is paired with an addition fact that has a missing number, so kids can count up.

What kids practice

Subtraction within 20 means taking away from a number that is 20 or less, like 15 - 7. These facts are harder than the ones within 10 because kids can't see them on two hands. Ten frames, number lines and addition facts they already know are what make them easy.

Watch for

  • Counting the starting number as the first hop, which gives an answer one too small.
  • Taking the smaller ones digit from the bigger one (13 - 5 becomes 12, because 5 - 3 = 2).
  • Losing track while counting back a long way. Counting up from the small number is usually shorter.

It's free to print, with Fewer, Standard or More on the page and an answer key. See the full subtraction within 20 guide for 1st grade.

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