← 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 51 · 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. 1.827 − 568 =
  2. 2.637 − 498 =
  3. 3.261 − 119 =
  4. 4.595 − 399 =
  5. 5.944 − 799 =
  6. 6.556 − 498 =
  7. 7.938 − 698 =
  8. 8.496 − 269 =
  9. 9.738 − 529 =
  10. 10.646 − 498 =
  11. 11.402 − 309 =
  12. 12.863 − 797 =
  13. 13.839 − 428 =
  14. 14.633 − 599 =
  15. 15.830 − 699 =
  16. 16.822 − 597 =
  17. 17.354 − 299 =
  18. 18.453 − 438 =
  19. 19.440 − 327 =
  20. 20.417 − 397 =
  21. 21.367 − 297 =
  22. 22.577 − 387 =
  23. 23.755 − 697 =
  24. 24.960 − 699 =
  25. 25.973 − 618 =
  26. 26.688 − 498 =
  27. 27.356 − 298 =
  28. 28.432 − 397 =
  29. 29.558 − 497 =
  30. 30.584 − 298 =
  31. 31.893 − 599 =
  32. 32.978 − 797 =
  33. 33.865 − 579 =
  34. 34.642 − 199 =
  35. 35.405 − 299 =
  36. 36.819 − 197 =
  37. 37.673 − 398 =
  38. 38.981 − 498 =
  39. 39.452 − 438 =
  40. 40.886 − 699 =

Answer key

  1. 259
  2. 139
  3. 142
  4. 196
  5. 145
  6. 58
  7. 240
  8. 227
  9. 209
  10. 148
  11. 93
  12. 66
  13. 411
  14. 34
  15. 131
  16. 225
  17. 55
  18. 15
  19. 113
  20. 20
  21. 70
  22. 190
  23. 58
  24. 261
  25. 355
  26. 190
  27. 58
  28. 35
  29. 61
  30. 286
  31. 294
  32. 181
  33. 286
  34. 443
  35. 106
  36. 622
  37. 275
  38. 483
  39. 14
  40. 187

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