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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 6 · 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. 1.789 − 298 =
  2. 2.782 − 499 =
  3. 3.723 − 478 =
  4. 4.849 − 327 =
  5. 5.483 − 199 =
  6. 6.775 − 669 =
  7. 7.647 − 309 =
  8. 8.717 − 599 =
  9. 9.889 − 697 =
  10. 10.871 − 588 =
  11. 11.763 − 398 =
  12. 12.448 − 268 =
  13. 13.836 − 799 =
  14. 14.522 − 199 =
  15. 15.897 − 399 =
  16. 16.933 − 598 =
  17. 17.699 − 118 =
  18. 18.965 − 399 =
  19. 19.958 − 379 =
  20. 20.373 − 268 =
  21. 21.787 − 298 =
  22. 22.932 − 799 =
  23. 23.903 − 328 =
  24. 24.524 − 469 =
  25. 25.893 − 187 =
  26. 26.315 − 199 =
  27. 27.350 − 318 =
  28. 28.692 − 518 =
  29. 29.986 − 799 =
  30. 30.665 − 198 =
  31. 31.560 − 499 =
  32. 32.628 − 608 =
  33. 33.701 − 597 =
  34. 34.910 − 497 =
  35. 35.247 − 197 =
  36. 36.583 − 498 =
  37. 37.267 − 197 =
  38. 38.836 − 697 =
  39. 39.827 − 518 =
  40. 40.520 − 297 =

Answer key

  1. 491
  2. 283
  3. 245
  4. 522
  5. 284
  6. 106
  7. 338
  8. 118
  9. 192
  10. 283
  11. 365
  12. 180
  13. 37
  14. 323
  15. 498
  16. 335
  17. 581
  18. 566
  19. 579
  20. 105
  21. 489
  22. 133
  23. 575
  24. 55
  25. 706
  26. 116
  27. 32
  28. 174
  29. 187
  30. 467
  31. 61
  32. 20
  33. 104
  34. 413
  35. 50
  36. 85
  37. 70
  38. 139
  39. 309
  40. 223

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