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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 504 · 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. 1.852 − 698 =
  2. 2.470 − 268 =
  3. 3.376 − 199 =
  4. 4.963 − 659 =
  5. 5.990 − 489 =
  6. 6.694 − 199 =
  7. 7.738 − 299 =
  8. 8.860 − 657 =
  9. 9.535 − 459 =
  10. 10.526 − 498 =
  11. 11.971 − 198 =
  12. 12.832 − 598 =
  13. 13.458 − 218 =
  14. 14.422 − 397 =
  15. 15.627 − 547 =
  16. 16.450 − 228 =
  17. 17.947 − 299 =
  18. 18.791 − 287 =
  19. 19.352 − 199 =
  20. 20.623 − 589 =
  21. 21.789 − 389 =
  22. 22.815 − 298 =
  23. 23.285 − 198 =
  24. 24.909 − 798 =
  25. 25.972 − 799 =
  26. 26.644 − 499 =
  27. 27.324 − 197 =
  28. 28.808 − 448 =
  29. 29.873 − 599 =
  30. 30.475 − 237 =
  31. 31.471 − 369 =
  32. 32.757 − 498 =
  33. 33.771 − 499 =
  34. 34.685 − 297 =
  35. 35.839 − 617 =
  36. 36.658 − 497 =
  37. 37.956 − 799 =
  38. 38.735 − 379 =
  39. 39.790 − 697 =
  40. 40.680 − 239 =

Answer key

  1. 154
  2. 202
  3. 177
  4. 304
  5. 501
  6. 495
  7. 439
  8. 203
  9. 76
  10. 28
  11. 773
  12. 234
  13. 240
  14. 25
  15. 80
  16. 222
  17. 648
  18. 504
  19. 153
  20. 34
  21. 400
  22. 517
  23. 87
  24. 111
  25. 173
  26. 145
  27. 127
  28. 360
  29. 274
  30. 238
  31. 102
  32. 259
  33. 272
  34. 388
  35. 222
  36. 161
  37. 157
  38. 356
  39. 93
  40. 441

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