Mental Math Strategies

Making tens

Practice Table of Contents


It is probably because humans have ten fingers that we have our familiar base-10 number system: ten ones make a ten; ten tens make a hundred; ten hundreds make a thousand. Because our number system is based on tens, making tens is a critical mental math skill. Here, we use ten-frames to visualize the process.

Step by step | Making tens

  1. Count up to the next ten. Remember this count.
  2. Add tens to the count until the goal is met.

Example | Making tens

Q: 7 + ____ = 20

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A: Counting up from 7, we count 3 more to reach 10. One more ten gives 20, for a total count of 13:
7 + 13 = 20.

Practice | Making tens