How to use this sheet

  • Before each problem, have the child look at every column and say whether it needs regrouping.
  • Model a few problems with base ten blocks so trading a ten for ten ones makes sense.
  • Check every answer by adding it to the number taken away. The total should be the top number.

Common mistakes

  • Subtracting the smaller digit from the larger in each column, so 52 − 17 becomes 45. When the top digit is smaller, regroup.
  • Regrouping but not crossing out and lowering the digit it came from, so the tens column is too big.
  • Getting stuck on zeros, as in 400 − 128. Regroup a hundred into 10 tens first, then a ten into 10 ones.
  • Regrouping when it is not needed, such as for 58 − 23. Check each column before starting.

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