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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 708 · 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. 1.980 − 798 =
  2. 2.336 − 197 =
  3. 3.809 − 668 =
  4. 4.841 − 698 =
  5. 5.748 − 569 =
  6. 6.529 − 449 =
  7. 7.658 − 498 =
  8. 8.569 − 489 =
  9. 9.901 − 349 =
  10. 10.222 − 169 =
  11. 11.732 − 359 =
  12. 12.541 − 419 =
  13. 13.677 − 118 =
  14. 14.933 − 388 =
  15. 15.641 − 459 =
  16. 16.786 − 697 =
  17. 17.652 − 497 =
  18. 18.514 − 439 =
  19. 19.745 − 399 =
  20. 20.969 − 399 =
  21. 21.530 − 197 =
  22. 22.643 − 588 =
  23. 23.645 − 199 =
  24. 24.976 − 797 =
  25. 25.913 − 507 =
  26. 26.960 − 797 =
  27. 27.876 − 649 =
  28. 28.642 − 487 =
  29. 29.903 − 289 =
  30. 30.876 − 497 =
  31. 31.818 − 517 =
  32. 32.564 − 537 =
  33. 33.872 − 629 =
  34. 34.550 − 198 =
  35. 35.955 − 698 =
  36. 36.792 − 399 =
  37. 37.858 − 228 =
  38. 38.644 − 199 =
  39. 39.553 − 368 =
  40. 40.726 − 557 =

Answer key

  1. 182
  2. 139
  3. 141
  4. 143
  5. 179
  6. 80
  7. 160
  8. 80
  9. 552
  10. 53
  11. 373
  12. 122
  13. 559
  14. 545
  15. 182
  16. 89
  17. 155
  18. 75
  19. 346
  20. 570
  21. 333
  22. 55
  23. 446
  24. 179
  25. 406
  26. 163
  27. 227
  28. 155
  29. 614
  30. 379
  31. 301
  32. 27
  33. 243
  34. 352
  35. 257
  36. 393
  37. 630
  38. 445
  39. 185
  40. 169

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