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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 156 · 40 questions
TalentJR

How to do it in your head (Round up, add back): Round the number you take away up to the next ten or hundred: 297 → 300 (3 too many). Take away the round number. Add back the extra, because you took away too much.

NameDateTime takenScore ___ / 40
  1. 1.453 − 297 =
  2. 2.857 − 799 =
  3. 3.916 − 597 =
  4. 4.654 − 257 =
  5. 5.962 − 798 =
  6. 6.735 − 199 =
  7. 7.780 − 199 =
  8. 8.966 − 699 =
  9. 9.758 − 638 =
  10. 10.901 − 129 =
  11. 11.971 − 797 =
  12. 12.742 − 699 =
  13. 13.524 − 377 =
  14. 14.459 − 398 =
  15. 15.675 − 477 =
  16. 16.306 − 127 =
  17. 17.657 − 529 =
  18. 18.730 − 319 =
  19. 19.385 − 348 =
  20. 20.767 − 299 =
  21. 21.964 − 177 =
  22. 22.937 − 599 =
  23. 23.702 − 197 =
  24. 24.721 − 568 =
  25. 25.893 − 299 =
  26. 26.853 − 799 =
  27. 27.894 − 217 =
  28. 28.964 − 267 =
  29. 29.636 − 599 =
  30. 30.858 − 499 =
  31. 31.534 − 499 =
  32. 32.678 − 298 =
  33. 33.806 − 679 =
  34. 34.652 − 567 =
  35. 35.609 − 198 =
  36. 36.542 − 499 =
  37. 37.831 − 397 =
  38. 38.502 − 397 =
  39. 39.785 − 379 =
  40. 40.398 − 118 =

Answer key

  1. 156
  2. 58
  3. 319
  4. 397
  5. 164
  6. 536
  7. 581
  8. 267
  9. 120
  10. 772
  11. 174
  12. 43
  13. 147
  14. 61
  15. 198
  16. 179
  17. 128
  18. 411
  19. 37
  20. 468
  21. 787
  22. 338
  23. 505
  24. 153
  25. 594
  26. 54
  27. 677
  28. 697
  29. 37
  30. 359
  31. 35
  32. 380
  33. 127
  34. 85
  35. 411
  36. 43
  37. 434
  38. 105
  39. 406
  40. 280

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