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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 154 · 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. 1.652 − 488 =
  2. 2.798 − 638 =
  3. 3.882 − 608 =
  4. 4.895 − 297 =
  5. 5.591 − 187 =
  6. 6.867 − 498 =
  7. 7.845 − 187 =
  8. 8.821 − 327 =
  9. 9.609 − 199 =
  10. 10.997 − 179 =
  11. 11.907 − 299 =
  12. 12.752 − 399 =
  13. 13.871 − 568 =
  14. 14.745 − 697 =
  15. 15.583 − 459 =
  16. 16.501 − 247 =
  17. 17.744 − 397 =
  18. 18.207 − 167 =
  19. 19.547 − 118 =
  20. 20.741 − 247 =
  21. 21.610 − 447 =
  22. 22.881 − 368 =
  23. 23.586 − 497 =
  24. 24.605 − 499 =
  25. 25.773 − 617 =
  26. 26.693 − 248 =
  27. 27.720 − 689 =
  28. 28.329 − 269 =
  29. 29.716 − 379 =
  30. 30.828 − 388 =
  31. 31.418 − 257 =
  32. 32.508 − 297 =
  33. 33.932 − 169 =
  34. 34.699 − 499 =
  35. 35.826 − 797 =
  36. 36.615 − 198 =
  37. 37.839 − 797 =
  38. 38.300 − 199 =
  39. 39.765 − 597 =
  40. 40.814 − 297 =

Answer key

  1. 164
  2. 160
  3. 274
  4. 598
  5. 404
  6. 369
  7. 658
  8. 494
  9. 410
  10. 818
  11. 608
  12. 353
  13. 303
  14. 48
  15. 124
  16. 254
  17. 347
  18. 40
  19. 429
  20. 494
  21. 163
  22. 513
  23. 89
  24. 106
  25. 156
  26. 445
  27. 31
  28. 60
  29. 337
  30. 440
  31. 161
  32. 211
  33. 763
  34. 200
  35. 29
  36. 417
  37. 42
  38. 101
  39. 168
  40. 517

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