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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 120 · 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. 1.830 − 567 =
  2. 2.756 − 329 =
  3. 3.709 − 138 =
  4. 4.770 − 599 =
  5. 5.999 − 599 =
  6. 6.653 − 557 =
  7. 7.822 − 668 =
  8. 8.817 − 687 =
  9. 9.767 − 517 =
  10. 10.650 − 517 =
  11. 11.790 − 618 =
  12. 12.813 − 197 =
  13. 13.647 − 539 =
  14. 14.957 − 197 =
  15. 15.268 − 199 =
  16. 16.865 − 608 =
  17. 17.897 − 299 =
  18. 18.666 − 297 =
  19. 19.660 − 508 =
  20. 20.704 − 599 =
  21. 21.450 − 297 =
  22. 22.316 − 157 =
  23. 23.889 − 697 =
  24. 24.730 − 398 =
  25. 25.298 − 157 =
  26. 26.919 − 697 =
  27. 27.747 − 597 =
  28. 28.898 − 399 =
  29. 29.393 − 277 =
  30. 30.783 − 499 =
  31. 31.851 − 799 =
  32. 32.784 − 669 =
  33. 33.995 − 487 =
  34. 34.594 − 247 =
  35. 35.951 − 219 =
  36. 36.896 − 698 =
  37. 37.845 − 298 =
  38. 38.626 − 597 =
  39. 39.859 − 799 =
  40. 40.572 − 199 =

Answer key

  1. 263
  2. 427
  3. 571
  4. 171
  5. 400
  6. 96
  7. 154
  8. 130
  9. 250
  10. 133
  11. 172
  12. 616
  13. 108
  14. 760
  15. 69
  16. 257
  17. 598
  18. 369
  19. 152
  20. 105
  21. 153
  22. 159
  23. 192
  24. 332
  25. 141
  26. 222
  27. 150
  28. 499
  29. 116
  30. 284
  31. 52
  32. 115
  33. 508
  34. 347
  35. 732
  36. 198
  37. 547
  38. 29
  39. 60
  40. 373

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