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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 369 · 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. 1.840 − 597 =
  2. 2.731 − 699 =
  3. 3.571 − 397 =
  4. 4.853 − 698 =
  5. 5.746 − 358 =
  6. 6.608 − 497 =
  7. 7.856 − 579 =
  8. 8.980 − 577 =
  9. 9.719 − 647 =
  10. 10.739 − 499 =
  11. 11.494 − 379 =
  12. 12.270 − 198 =
  13. 13.927 − 189 =
  14. 14.896 − 397 =
  15. 15.827 − 799 =
  16. 16.826 − 538 =
  17. 17.479 − 128 =
  18. 18.969 − 308 =
  19. 19.746 − 399 =
  20. 20.786 − 698 =
  21. 21.465 − 158 =
  22. 22.979 − 499 =
  23. 23.353 − 197 =
  24. 24.956 − 698 =
  25. 25.727 − 459 =
  26. 26.537 − 499 =
  27. 27.331 − 178 =
  28. 28.634 − 597 =
  29. 29.602 − 499 =
  30. 30.650 − 419 =
  31. 31.790 − 147 =
  32. 32.978 − 398 =
  33. 33.537 − 299 =
  34. 34.460 − 297 =
  35. 35.860 − 599 =
  36. 36.313 − 297 =
  37. 37.889 − 657 =
  38. 38.707 − 129 =
  39. 39.872 − 197 =
  40. 40.659 − 497 =

Answer key

  1. 243
  2. 32
  3. 174
  4. 155
  5. 388
  6. 111
  7. 277
  8. 403
  9. 72
  10. 240
  11. 115
  12. 72
  13. 738
  14. 499
  15. 28
  16. 288
  17. 351
  18. 661
  19. 347
  20. 88
  21. 307
  22. 480
  23. 156
  24. 258
  25. 268
  26. 38
  27. 153
  28. 37
  29. 103
  30. 231
  31. 643
  32. 580
  33. 238
  34. 163
  35. 261
  36. 16
  37. 232
  38. 578
  39. 675
  40. 162

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