← 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 366 · 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. 1.811 − 598 =
  2. 2.988 − 397 =
  3. 3.596 − 299 =
  4. 4.943 − 488 =
  5. 5.959 − 397 =
  6. 6.702 − 597 =
  7. 7.486 − 299 =
  8. 8.626 − 599 =
  9. 9.772 − 699 =
  10. 10.987 − 209 =
  11. 11.525 − 197 =
  12. 12.937 − 598 =
  13. 13.914 − 667 =
  14. 14.709 − 497 =
  15. 15.938 − 798 =
  16. 16.736 − 198 =
  17. 17.790 − 298 =
  18. 18.582 − 499 =
  19. 19.656 − 168 =
  20. 20.532 − 498 =
  21. 21.709 − 598 =
  22. 22.353 − 299 =
  23. 23.837 − 567 =
  24. 24.271 − 198 =
  25. 25.595 − 448 =
  26. 26.816 − 577 =
  27. 27.881 − 199 =
  28. 28.844 − 799 =
  29. 29.461 − 297 =
  30. 30.541 − 227 =
  31. 31.813 − 257 =
  32. 32.858 − 499 =
  33. 33.555 − 299 =
  34. 34.811 − 388 =
  35. 35.315 − 197 =
  36. 36.931 − 499 =
  37. 37.630 − 289 =
  38. 38.916 − 797 =
  39. 39.526 − 339 =
  40. 40.990 − 618 =

Answer key

  1. 213
  2. 591
  3. 297
  4. 455
  5. 562
  6. 105
  7. 187
  8. 27
  9. 73
  10. 778
  11. 328
  12. 339
  13. 247
  14. 212
  15. 140
  16. 538
  17. 492
  18. 83
  19. 488
  20. 34
  21. 111
  22. 54
  23. 270
  24. 73
  25. 147
  26. 239
  27. 682
  28. 45
  29. 164
  30. 314
  31. 556
  32. 359
  33. 256
  34. 423
  35. 118
  36. 432
  37. 341
  38. 119
  39. 187
  40. 372

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