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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 43 · 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. 1.854 − 797 =
  2. 2.630 − 298 =
  3. 3.734 − 699 =
  4. 4.534 − 438 =
  5. 5.803 − 198 =
  6. 6.459 − 207 =
  7. 7.640 − 129 =
  8. 8.738 − 699 =
  9. 9.627 − 337 =
  10. 10.409 − 177 =
  11. 11.723 − 368 =
  12. 12.727 − 637 =
  13. 13.587 − 358 =
  14. 14.416 − 297 =
  15. 15.520 − 219 =
  16. 16.598 − 299 =
  17. 17.969 − 658 =
  18. 18.222 − 189 =
  19. 19.926 − 799 =
  20. 20.657 − 619 =
  21. 21.926 − 299 =
  22. 22.912 − 497 =
  23. 23.300 − 199 =
  24. 24.573 − 329 =
  25. 25.597 − 258 =
  26. 26.653 − 517 =
  27. 27.940 − 798 =
  28. 28.797 − 529 =
  29. 29.688 − 497 =
  30. 30.887 − 798 =
  31. 31.915 − 699 =
  32. 32.977 − 198 =
  33. 33.682 − 158 =
  34. 34.701 − 519 =
  35. 35.690 − 187 =
  36. 36.407 − 298 =
  37. 37.956 − 197 =
  38. 38.350 − 138 =
  39. 39.705 − 597 =
  40. 40.783 − 519 =

Answer key

  1. 57
  2. 332
  3. 35
  4. 96
  5. 605
  6. 252
  7. 511
  8. 39
  9. 290
  10. 232
  11. 355
  12. 90
  13. 229
  14. 119
  15. 301
  16. 299
  17. 311
  18. 33
  19. 127
  20. 38
  21. 627
  22. 415
  23. 101
  24. 244
  25. 339
  26. 136
  27. 142
  28. 268
  29. 191
  30. 89
  31. 216
  32. 779
  33. 524
  34. 182
  35. 503
  36. 109
  37. 759
  38. 212
  39. 108
  40. 264

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