← 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 303 · 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. 1.676 − 297 =
  2. 2.851 − 498 =
  3. 3.751 − 597 =
  4. 4.839 − 499 =
  5. 5.562 − 358 =
  6. 6.815 − 299 =
  7. 7.687 − 139 =
  8. 8.889 − 599 =
  9. 9.682 − 199 =
  10. 10.956 − 618 =
  11. 11.737 − 659 =
  12. 12.889 − 698 =
  13. 13.749 − 699 =
  14. 14.806 − 239 =
  15. 15.921 − 697 =
  16. 16.998 − 599 =
  17. 17.773 − 399 =
  18. 18.790 − 199 =
  19. 19.443 − 368 =
  20. 20.694 − 289 =
  21. 21.763 − 598 =
  22. 22.845 − 599 =
  23. 23.754 − 697 =
  24. 24.876 − 798 =
  25. 25.508 − 339 =
  26. 26.355 − 197 =
  27. 27.914 − 799 =
  28. 28.481 − 398 =
  29. 29.935 − 299 =
  30. 30.932 − 199 =
  31. 31.355 − 297 =
  32. 32.811 − 199 =
  33. 33.735 − 599 =
  34. 34.829 − 798 =
  35. 35.392 − 359 =
  36. 36.815 − 799 =
  37. 37.317 − 297 =
  38. 38.629 − 547 =
  39. 39.724 − 577 =
  40. 40.829 − 599 =

Answer key

  1. 379
  2. 353
  3. 154
  4. 340
  5. 204
  6. 516
  7. 548
  8. 290
  9. 483
  10. 338
  11. 78
  12. 191
  13. 50
  14. 567
  15. 224
  16. 399
  17. 374
  18. 591
  19. 75
  20. 405
  21. 165
  22. 246
  23. 57
  24. 78
  25. 169
  26. 158
  27. 115
  28. 83
  29. 636
  30. 733
  31. 58
  32. 612
  33. 136
  34. 31
  35. 33
  36. 16
  37. 20
  38. 82
  39. 147
  40. 230

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