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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 950 · 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. 1.173 − 158 =
  2. 2.538 − 499 =
  3. 3.425 − 297 =
  4. 4.920 − 518 =
  5. 5.748 − 637 =
  6. 6.935 − 799 =
  7. 7.730 − 499 =
  8. 8.549 − 299 =
  9. 9.913 − 799 =
  10. 10.838 − 508 =
  11. 11.325 − 258 =
  12. 12.773 − 699 =
  13. 13.779 − 697 =
  14. 14.941 − 249 =
  15. 15.976 − 597 =
  16. 16.754 − 559 =
  17. 17.760 − 699 =
  18. 18.579 − 199 =
  19. 19.571 − 528 =
  20. 20.335 − 139 =
  21. 21.576 − 498 =
  22. 22.514 − 267 =
  23. 23.731 − 699 =
  24. 24.984 − 797 =
  25. 25.717 − 548 =
  26. 26.782 − 699 =
  27. 27.523 − 398 =
  28. 28.822 − 798 =
  29. 29.956 − 639 =
  30. 30.757 − 598 =
  31. 31.815 − 797 =
  32. 32.515 − 309 =
  33. 33.983 − 169 =
  34. 34.802 − 597 =
  35. 35.986 − 398 =
  36. 36.631 − 577 =
  37. 37.855 − 597 =
  38. 38.974 − 488 =
  39. 39.641 − 607 =
  40. 40.738 − 199 =

Answer key

  1. 15
  2. 39
  3. 128
  4. 402
  5. 111
  6. 136
  7. 231
  8. 250
  9. 114
  10. 330
  11. 67
  12. 74
  13. 82
  14. 692
  15. 379
  16. 195
  17. 61
  18. 380
  19. 43
  20. 196
  21. 78
  22. 247
  23. 32
  24. 187
  25. 169
  26. 83
  27. 125
  28. 24
  29. 317
  30. 159
  31. 18
  32. 206
  33. 814
  34. 205
  35. 588
  36. 54
  37. 258
  38. 486
  39. 34
  40. 539

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