← 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 222 · 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. 1.850 − 597 =
  2. 2.914 − 549 =
  3. 3.977 − 598 =
  4. 4.659 − 498 =
  5. 5.665 − 399 =
  6. 6.514 − 399 =
  7. 7.332 − 117 =
  8. 8.525 − 398 =
  9. 9.494 − 198 =
  10. 10.173 − 159 =
  11. 11.604 − 398 =
  12. 12.529 − 498 =
  13. 13.610 − 397 =
  14. 14.798 − 498 =
  15. 15.726 − 699 =
  16. 16.890 − 278 =
  17. 17.503 − 197 =
  18. 18.566 − 398 =
  19. 19.940 − 299 =
  20. 20.779 − 598 =
  21. 21.250 − 218 =
  22. 22.913 − 699 =
  23. 23.891 − 607 =
  24. 24.424 − 218 =
  25. 25.624 − 547 =
  26. 26.948 − 199 =
  27. 27.896 − 697 =
  28. 28.528 − 349 =
  29. 29.826 − 299 =
  30. 30.521 − 429 =
  31. 31.842 − 799 =
  32. 32.435 − 298 =
  33. 33.532 − 499 =
  34. 34.787 − 698 =
  35. 35.982 − 598 =
  36. 36.312 − 299 =
  37. 37.448 − 398 =
  38. 38.560 − 198 =
  39. 39.652 − 609 =
  40. 40.649 − 499 =

Answer key

  1. 253
  2. 365
  3. 379
  4. 161
  5. 266
  6. 115
  7. 215
  8. 127
  9. 296
  10. 14
  11. 206
  12. 31
  13. 213
  14. 300
  15. 27
  16. 612
  17. 306
  18. 168
  19. 641
  20. 181
  21. 32
  22. 214
  23. 284
  24. 206
  25. 77
  26. 749
  27. 199
  28. 179
  29. 527
  30. 92
  31. 43
  32. 137
  33. 33
  34. 89
  35. 384
  36. 13
  37. 50
  38. 362
  39. 43
  40. 150

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