← 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 750 · 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. 1.775 − 508 =
  2. 2.818 − 399 =
  3. 3.867 − 798 =
  4. 4.501 − 368 =
  5. 5.948 − 579 =
  6. 6.671 − 318 =
  7. 7.877 − 499 =
  8. 8.963 − 799 =
  9. 9.966 − 598 =
  10. 10.294 − 128 =
  11. 11.758 − 438 =
  12. 12.915 − 299 =
  13. 13.855 − 798 =
  14. 14.733 − 277 =
  15. 15.360 − 298 =
  16. 16.766 − 657 =
  17. 17.537 − 478 =
  18. 18.780 − 598 =
  19. 19.909 − 398 =
  20. 20.688 − 279 =
  21. 21.509 − 348 =
  22. 22.232 − 159 =
  23. 23.854 − 139 =
  24. 24.979 − 297 =
  25. 25.313 − 249 =
  26. 26.345 − 197 =
  27. 27.579 − 117 =
  28. 28.931 − 597 =
  29. 29.941 − 799 =
  30. 30.907 − 637 =
  31. 31.935 − 797 =
  32. 32.817 − 798 =
  33. 33.931 − 588 =
  34. 34.952 − 798 =
  35. 35.876 − 798 =
  36. 36.416 − 297 =
  37. 37.397 − 298 =
  38. 38.922 − 197 =
  39. 39.372 − 247 =
  40. 40.813 − 657 =

Answer key

  1. 267
  2. 419
  3. 69
  4. 133
  5. 369
  6. 353
  7. 378
  8. 164
  9. 368
  10. 166
  11. 320
  12. 616
  13. 57
  14. 456
  15. 62
  16. 109
  17. 59
  18. 182
  19. 511
  20. 409
  21. 161
  22. 73
  23. 715
  24. 682
  25. 64
  26. 148
  27. 462
  28. 334
  29. 142
  30. 270
  31. 138
  32. 19
  33. 343
  34. 154
  35. 78
  36. 119
  37. 99
  38. 725
  39. 125
  40. 156

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