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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 964 · 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. 1.869 − 677 =
  2. 2.981 − 498 =
  3. 3.992 − 197 =
  4. 4.542 − 299 =
  5. 5.816 − 237 =
  6. 6.864 − 618 =
  7. 7.571 − 499 =
  8. 8.860 − 197 =
  9. 9.740 − 698 =
  10. 10.863 − 458 =
  11. 11.820 − 597 =
  12. 12.731 − 368 =
  13. 13.876 − 799 =
  14. 14.650 − 397 =
  15. 15.824 − 397 =
  16. 16.832 − 698 =
  17. 17.533 − 489 =
  18. 18.660 − 597 =
  19. 19.569 − 498 =
  20. 20.677 − 599 =
  21. 21.721 − 638 =
  22. 22.818 − 458 =
  23. 23.689 − 619 =
  24. 24.801 − 299 =
  25. 25.751 − 529 =
  26. 26.522 − 499 =
  27. 27.570 − 517 =
  28. 28.632 − 197 =
  29. 29.908 − 798 =
  30. 30.989 − 697 =
  31. 31.308 − 197 =
  32. 32.956 − 468 =
  33. 33.692 − 198 =
  34. 34.554 − 198 =
  35. 35.838 − 799 =
  36. 36.324 − 249 =
  37. 37.390 − 359 =
  38. 38.825 − 258 =
  39. 39.625 − 199 =
  40. 40.484 − 197 =

Answer key

  1. 192
  2. 483
  3. 795
  4. 243
  5. 579
  6. 246
  7. 72
  8. 663
  9. 42
  10. 405
  11. 223
  12. 363
  13. 77
  14. 253
  15. 427
  16. 134
  17. 44
  18. 63
  19. 71
  20. 78
  21. 83
  22. 360
  23. 70
  24. 502
  25. 222
  26. 23
  27. 53
  28. 435
  29. 110
  30. 292
  31. 111
  32. 488
  33. 494
  34. 356
  35. 39
  36. 75
  37. 31
  38. 567
  39. 426
  40. 287

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