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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 991 · 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. 1.766 − 199 =
  2. 2.866 − 399 =
  3. 3.653 − 429 =
  4. 4.851 − 398 =
  5. 5.509 − 299 =
  6. 6.598 − 299 =
  7. 7.641 − 597 =
  8. 8.711 − 659 =
  9. 9.724 − 699 =
  10. 10.808 − 198 =
  11. 11.842 − 597 =
  12. 12.463 − 299 =
  13. 13.641 − 397 =
  14. 14.701 − 297 =
  15. 15.839 − 677 =
  16. 16.849 − 397 =
  17. 17.634 − 399 =
  18. 18.907 − 397 =
  19. 19.559 − 498 =
  20. 20.702 − 378 =
  21. 21.919 − 178 =
  22. 22.858 − 297 =
  23. 23.771 − 548 =
  24. 24.383 − 247 =
  25. 25.501 − 418 =
  26. 26.571 − 498 =
  27. 27.977 − 298 =
  28. 28.585 − 499 =
  29. 29.693 − 498 =
  30. 30.960 − 559 =
  31. 31.652 − 497 =
  32. 32.613 − 497 =
  33. 33.599 − 398 =
  34. 34.564 − 509 =
  35. 35.561 − 199 =
  36. 36.809 − 207 =
  37. 37.908 − 497 =
  38. 38.538 − 267 =
  39. 39.900 − 127 =
  40. 40.675 − 299 =

Answer key

  1. 567
  2. 467
  3. 224
  4. 453
  5. 210
  6. 299
  7. 44
  8. 52
  9. 25
  10. 610
  11. 245
  12. 164
  13. 244
  14. 404
  15. 162
  16. 452
  17. 235
  18. 510
  19. 61
  20. 324
  21. 741
  22. 561
  23. 223
  24. 136
  25. 83
  26. 73
  27. 679
  28. 86
  29. 195
  30. 401
  31. 155
  32. 116
  33. 201
  34. 55
  35. 362
  36. 602
  37. 411
  38. 271
  39. 773
  40. 376

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