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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 702 · 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. 1.851 − 497 =
  2. 2.395 − 198 =
  3. 3.808 − 678 =
  4. 4.609 − 509 =
  5. 5.306 − 198 =
  6. 6.833 − 398 =
  7. 7.864 − 299 =
  8. 8.929 − 798 =
  9. 9.828 − 299 =
  10. 10.624 − 307 =
  11. 11.873 − 548 =
  12. 12.730 − 697 =
  13. 13.939 − 798 =
  14. 14.562 − 397 =
  15. 15.415 − 199 =
  16. 16.965 − 497 =
  17. 17.500 − 298 =
  18. 18.461 − 328 =
  19. 19.632 − 499 =
  20. 20.911 − 339 =
  21. 21.761 − 689 =
  22. 22.267 − 179 =
  23. 23.816 − 497 =
  24. 24.620 − 598 =
  25. 25.870 − 798 =
  26. 26.397 − 179 =
  27. 27.244 − 199 =
  28. 28.659 − 447 =
  29. 29.610 − 199 =
  30. 30.977 − 639 =
  31. 31.581 − 498 =
  32. 32.723 − 599 =
  33. 33.291 − 158 =
  34. 34.987 − 299 =
  35. 35.416 − 179 =
  36. 36.985 − 699 =
  37. 37.409 − 267 =
  38. 38.594 − 468 =
  39. 39.776 − 197 =
  40. 40.971 − 279 =

Answer key

  1. 354
  2. 197
  3. 130
  4. 100
  5. 108
  6. 435
  7. 565
  8. 131
  9. 529
  10. 317
  11. 325
  12. 33
  13. 141
  14. 165
  15. 216
  16. 468
  17. 202
  18. 133
  19. 133
  20. 572
  21. 72
  22. 88
  23. 319
  24. 22
  25. 72
  26. 218
  27. 45
  28. 212
  29. 411
  30. 338
  31. 83
  32. 124
  33. 133
  34. 688
  35. 237
  36. 286
  37. 142
  38. 126
  39. 579
  40. 692

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