← 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 357 · 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. 1.824 − 298 =
  2. 2.751 − 529 =
  3. 3.646 − 199 =
  4. 4.839 − 797 =
  5. 5.545 − 149 =
  6. 6.351 − 237 =
  7. 7.471 − 399 =
  8. 8.975 − 588 =
  9. 9.698 − 179 =
  10. 10.531 − 237 =
  11. 11.795 − 639 =
  12. 12.849 − 699 =
  13. 13.611 − 539 =
  14. 14.508 − 397 =
  15. 15.848 − 698 =
  16. 16.978 − 699 =
  17. 17.867 − 798 =
  18. 18.886 − 197 =
  19. 19.834 − 799 =
  20. 20.650 − 299 =
  21. 21.718 − 147 =
  22. 22.601 − 199 =
  23. 23.960 − 298 =
  24. 24.687 − 657 =
  25. 25.607 − 498 =
  26. 26.939 − 799 =
  27. 27.743 − 659 =
  28. 28.632 − 598 =
  29. 29.830 − 678 =
  30. 30.452 − 198 =
  31. 31.543 − 488 =
  32. 32.502 − 399 =
  33. 33.187 − 117 =
  34. 34.669 − 148 =
  35. 35.767 − 598 =
  36. 36.799 − 309 =
  37. 37.941 − 657 =
  38. 38.766 − 398 =
  39. 39.748 − 488 =
  40. 40.851 − 599 =

Answer key

  1. 526
  2. 222
  3. 447
  4. 42
  5. 396
  6. 114
  7. 72
  8. 387
  9. 519
  10. 294
  11. 156
  12. 150
  13. 72
  14. 111
  15. 150
  16. 279
  17. 69
  18. 689
  19. 35
  20. 351
  21. 571
  22. 402
  23. 662
  24. 30
  25. 109
  26. 140
  27. 84
  28. 34
  29. 152
  30. 254
  31. 55
  32. 103
  33. 70
  34. 521
  35. 169
  36. 490
  37. 284
  38. 368
  39. 260
  40. 252

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