← Subtract by rounding up and adding back lesson New set →

Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 764 · 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. 1.631 − 327 =
  2. 2.998 − 698 =
  3. 3.932 − 298 =
  4. 4.852 − 397 =
  5. 5.650 − 598 =
  6. 6.458 − 397 =
  7. 7.448 − 399 =
  8. 8.627 − 498 =
  9. 9.513 − 399 =
  10. 10.535 − 497 =
  11. 11.483 − 359 =
  12. 12.755 − 698 =
  13. 13.970 − 188 =
  14. 14.846 − 499 =
  15. 15.672 − 418 =
  16. 16.412 − 297 =
  17. 17.355 − 298 =
  18. 18.847 − 239 =
  19. 19.305 − 199 =
  20. 20.768 − 268 =
  21. 21.780 − 659 =
  22. 22.696 − 169 =
  23. 23.959 − 408 =
  24. 24.574 − 537 =
  25. 25.478 − 199 =
  26. 26.416 − 397 =
  27. 27.980 − 668 =
  28. 28.908 − 559 =
  29. 29.848 − 798 =
  30. 30.487 − 387 =
  31. 31.863 − 279 =
  32. 32.766 − 288 =
  33. 33.311 − 149 =
  34. 34.825 − 689 =
  35. 35.717 − 597 =
  36. 36.952 − 798 =
  37. 37.937 − 699 =
  38. 38.852 − 798 =
  39. 39.932 − 397 =
  40. 40.422 − 399 =

Answer key

  1. 304
  2. 300
  3. 634
  4. 455
  5. 52
  6. 61
  7. 49
  8. 129
  9. 114
  10. 38
  11. 124
  12. 57
  13. 782
  14. 347
  15. 254
  16. 115
  17. 57
  18. 608
  19. 106
  20. 500
  21. 121
  22. 527
  23. 551
  24. 37
  25. 279
  26. 19
  27. 312
  28. 349
  29. 50
  30. 100
  31. 584
  32. 478
  33. 162
  34. 136
  35. 120
  36. 154
  37. 238
  38. 54
  39. 535
  40. 23

Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths