← 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 941 · 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. 1.642 − 409 =
  2. 2.984 − 597 =
  3. 3.906 − 297 =
  4. 4.528 − 398 =
  5. 5.839 − 679 =
  6. 6.583 − 448 =
  7. 7.694 − 498 =
  8. 8.679 − 199 =
  9. 9.897 − 498 =
  10. 10.571 − 399 =
  11. 11.765 − 659 =
  12. 12.728 − 197 =
  13. 13.712 − 587 =
  14. 14.857 − 697 =
  15. 15.716 − 199 =
  16. 16.712 − 697 =
  17. 17.596 − 399 =
  18. 18.427 − 398 =
  19. 19.853 − 378 =
  20. 20.728 − 698 =
  21. 21.875 − 799 =
  22. 22.748 − 558 =
  23. 23.841 − 799 =
  24. 24.953 − 698 =
  25. 25.529 − 298 =
  26. 26.799 − 698 =
  27. 27.747 − 569 =
  28. 28.546 − 248 =
  29. 29.907 − 649 =
  30. 30.721 − 638 =
  31. 31.323 − 299 =
  32. 32.683 − 399 =
  33. 33.596 − 197 =
  34. 34.315 − 198 =
  35. 35.683 − 597 =
  36. 36.550 − 198 =
  37. 37.706 − 298 =
  38. 38.904 − 799 =
  39. 39.886 − 797 =
  40. 40.810 − 629 =

Answer key

  1. 233
  2. 387
  3. 609
  4. 130
  5. 160
  6. 135
  7. 196
  8. 480
  9. 399
  10. 172
  11. 106
  12. 531
  13. 125
  14. 160
  15. 517
  16. 15
  17. 197
  18. 29
  19. 475
  20. 30
  21. 76
  22. 190
  23. 42
  24. 255
  25. 231
  26. 101
  27. 178
  28. 298
  29. 258
  30. 83
  31. 24
  32. 284
  33. 399
  34. 117
  35. 86
  36. 352
  37. 408
  38. 105
  39. 89
  40. 181

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