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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 219 · 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. 1.859 − 699 =
  2. 2.469 − 369 =
  3. 3.896 − 797 =
  4. 4.973 − 697 =
  5. 5.512 − 369 =
  6. 6.789 − 597 =
  7. 7.814 − 797 =
  8. 8.950 − 699 =
  9. 9.905 − 397 =
  10. 10.934 − 798 =
  11. 11.268 − 199 =
  12. 12.863 − 337 =
  13. 13.214 − 199 =
  14. 14.835 − 298 =
  15. 15.896 − 397 =
  16. 16.912 − 599 =
  17. 17.633 − 558 =
  18. 18.851 − 399 =
  19. 19.524 − 468 =
  20. 20.670 − 549 =
  21. 21.589 − 559 =
  22. 22.726 − 579 =
  23. 23.925 − 799 =
  24. 24.575 − 559 =
  25. 25.399 − 299 =
  26. 26.888 − 499 =
  27. 27.634 − 597 =
  28. 28.246 − 198 =
  29. 29.328 − 137 =
  30. 30.693 − 199 =
  31. 31.937 − 319 =
  32. 32.902 − 799 =
  33. 33.605 − 238 =
  34. 34.547 − 197 =
  35. 35.587 − 299 =
  36. 36.703 − 298 =
  37. 37.889 − 218 =
  38. 38.969 − 798 =
  39. 39.988 − 599 =
  40. 40.754 − 599 =

Answer key

  1. 160
  2. 100
  3. 99
  4. 276
  5. 143
  6. 192
  7. 17
  8. 251
  9. 508
  10. 136
  11. 69
  12. 526
  13. 15
  14. 537
  15. 499
  16. 313
  17. 75
  18. 452
  19. 56
  20. 121
  21. 30
  22. 147
  23. 126
  24. 16
  25. 100
  26. 389
  27. 37
  28. 48
  29. 191
  30. 494
  31. 618
  32. 103
  33. 367
  34. 350
  35. 288
  36. 405
  37. 671
  38. 171
  39. 389
  40. 155

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