← 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 753 · 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. 1.231 − 198 =
  2. 2.389 − 307 =
  3. 3.951 − 179 =
  4. 4.840 − 209 =
  5. 5.793 − 499 =
  6. 6.370 − 157 =
  7. 7.261 − 197 =
  8. 8.421 − 179 =
  9. 9.763 − 497 =
  10. 10.971 − 358 =
  11. 11.785 − 699 =
  12. 12.592 − 198 =
  13. 13.813 − 667 =
  14. 14.224 − 179 =
  15. 15.900 − 438 =
  16. 16.852 − 309 =
  17. 17.346 − 298 =
  18. 18.933 − 429 =
  19. 19.931 − 298 =
  20. 20.840 − 237 =
  21. 21.501 − 398 =
  22. 22.304 − 198 =
  23. 23.903 − 569 =
  24. 24.726 − 297 =
  25. 25.253 − 197 =
  26. 26.507 − 427 =
  27. 27.754 − 298 =
  28. 28.785 − 619 =
  29. 29.590 − 297 =
  30. 30.680 − 198 =
  31. 31.989 − 639 =
  32. 32.906 − 597 =
  33. 33.846 − 369 =
  34. 34.916 − 687 =
  35. 35.990 − 498 =
  36. 36.537 − 239 =
  37. 37.875 − 298 =
  38. 38.349 − 309 =
  39. 39.885 − 598 =
  40. 40.628 − 329 =

Answer key

  1. 33
  2. 82
  3. 772
  4. 631
  5. 294
  6. 213
  7. 64
  8. 242
  9. 266
  10. 613
  11. 86
  12. 394
  13. 146
  14. 45
  15. 462
  16. 543
  17. 48
  18. 504
  19. 633
  20. 603
  21. 103
  22. 106
  23. 334
  24. 429
  25. 56
  26. 80
  27. 456
  28. 166
  29. 293
  30. 482
  31. 350
  32. 309
  33. 477
  34. 229
  35. 492
  36. 298
  37. 577
  38. 40
  39. 287
  40. 299

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