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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 341 · 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. 1.863 − 398 =
  2. 2.831 − 698 =
  3. 3.731 − 487 =
  4. 4.638 − 497 =
  5. 5.974 − 469 =
  6. 6.868 − 597 =
  7. 7.379 − 289 =
  8. 8.726 − 697 =
  9. 9.682 − 217 =
  10. 10.517 − 378 =
  11. 11.958 − 297 =
  12. 12.493 − 279 =
  13. 13.676 − 337 =
  14. 14.160 − 118 =
  15. 15.975 − 397 =
  16. 16.718 − 499 =
  17. 17.599 − 519 =
  18. 18.755 − 478 =
  19. 19.646 − 499 =
  20. 20.601 − 459 =
  21. 21.246 − 219 =
  22. 22.434 − 389 =
  23. 23.966 − 798 =
  24. 24.713 − 179 =
  25. 25.970 − 608 =
  26. 26.464 − 399 =
  27. 27.628 − 598 =
  28. 28.973 − 127 =
  29. 29.763 − 419 =
  30. 30.909 − 607 =
  31. 31.524 − 498 =
  32. 32.881 − 799 =
  33. 33.711 − 499 =
  34. 34.740 − 689 =
  35. 35.879 − 398 =
  36. 36.418 − 189 =
  37. 37.410 − 199 =
  38. 38.460 − 298 =
  39. 39.574 − 189 =
  40. 40.584 − 497 =

Answer key

  1. 465
  2. 133
  3. 244
  4. 141
  5. 505
  6. 271
  7. 90
  8. 29
  9. 465
  10. 139
  11. 661
  12. 214
  13. 339
  14. 42
  15. 578
  16. 219
  17. 80
  18. 277
  19. 147
  20. 142
  21. 27
  22. 45
  23. 168
  24. 534
  25. 362
  26. 65
  27. 30
  28. 846
  29. 344
  30. 302
  31. 26
  32. 82
  33. 212
  34. 51
  35. 481
  36. 229
  37. 211
  38. 162
  39. 385
  40. 87

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