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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 18 · 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. 1.659 − 599 =
  2. 2.863 − 687 =
  3. 3.838 − 467 =
  4. 4.373 − 317 =
  5. 5.949 − 298 =
  6. 6.683 − 518 =
  7. 7.876 − 399 =
  8. 8.941 − 407 =
  9. 9.734 − 507 =
  10. 10.921 − 798 =
  11. 11.824 − 519 =
  12. 12.418 − 299 =
  13. 13.957 − 329 =
  14. 14.912 − 599 =
  15. 15.845 − 699 =
  16. 16.833 − 149 =
  17. 17.603 − 299 =
  18. 18.674 − 197 =
  19. 19.586 − 489 =
  20. 20.447 − 297 =
  21. 21.833 − 499 =
  22. 22.924 − 579 =
  23. 23.597 − 397 =
  24. 24.346 − 208 =
  25. 25.442 − 299 =
  26. 26.687 − 419 =
  27. 27.750 − 299 =
  28. 28.446 − 199 =
  29. 29.399 − 299 =
  30. 30.712 − 659 =
  31. 31.946 − 528 =
  32. 32.583 − 299 =
  33. 33.991 − 798 =
  34. 34.667 − 559 =
  35. 35.286 − 169 =
  36. 36.690 − 398 =
  37. 37.850 − 387 =
  38. 38.954 − 477 =
  39. 39.442 − 297 =
  40. 40.414 − 349 =

Answer key

  1. 60
  2. 176
  3. 371
  4. 56
  5. 651
  6. 165
  7. 477
  8. 534
  9. 227
  10. 123
  11. 305
  12. 119
  13. 628
  14. 313
  15. 146
  16. 684
  17. 304
  18. 477
  19. 97
  20. 150
  21. 334
  22. 345
  23. 200
  24. 138
  25. 143
  26. 268
  27. 451
  28. 247
  29. 100
  30. 53
  31. 418
  32. 284
  33. 193
  34. 108
  35. 117
  36. 292
  37. 463
  38. 477
  39. 145
  40. 65

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