← 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 140 · 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. 1.989 − 278 =
  2. 2.459 − 398 =
  3. 3.629 − 297 =
  4. 4.648 − 598 =
  5. 5.504 − 427 =
  6. 6.420 − 298 =
  7. 7.935 − 478 =
  8. 8.907 − 699 =
  9. 9.946 − 297 =
  10. 10.913 − 348 =
  11. 11.755 − 477 =
  12. 12.599 − 499 =
  13. 13.992 − 597 =
  14. 14.564 − 397 =
  15. 15.802 − 628 =
  16. 16.766 − 198 =
  17. 17.668 − 298 =
  18. 18.835 − 797 =
  19. 19.671 − 607 =
  20. 20.662 − 227 =
  21. 21.964 − 138 =
  22. 22.887 − 569 =
  23. 23.896 − 597 =
  24. 24.814 − 698 =
  25. 25.546 − 478 =
  26. 26.957 − 299 =
  27. 27.550 − 499 =
  28. 28.743 − 597 =
  29. 29.945 − 619 =
  30. 30.593 − 497 =
  31. 31.991 − 348 =
  32. 32.369 − 258 =
  33. 33.590 − 197 =
  34. 34.910 − 169 =
  35. 35.690 − 499 =
  36. 36.784 − 679 =
  37. 37.857 − 699 =
  38. 38.507 − 359 =
  39. 39.555 − 397 =
  40. 40.570 − 197 =

Answer key

  1. 711
  2. 61
  3. 332
  4. 50
  5. 77
  6. 122
  7. 457
  8. 208
  9. 649
  10. 565
  11. 278
  12. 100
  13. 395
  14. 167
  15. 174
  16. 568
  17. 370
  18. 38
  19. 64
  20. 435
  21. 826
  22. 318
  23. 299
  24. 116
  25. 68
  26. 658
  27. 51
  28. 146
  29. 326
  30. 96
  31. 643
  32. 111
  33. 393
  34. 741
  35. 191
  36. 105
  37. 158
  38. 148
  39. 158
  40. 373

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