← 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 361 · 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. 1.858 − 797 =
  2. 2.389 − 299 =
  3. 3.824 − 477 =
  4. 4.290 − 197 =
  5. 5.919 − 429 =
  6. 6.358 − 137 =
  7. 7.434 − 147 =
  8. 8.670 − 469 =
  9. 9.742 − 569 =
  10. 10.577 − 527 =
  11. 11.241 − 198 =
  12. 12.387 − 297 =
  13. 13.456 − 298 =
  14. 14.591 − 259 =
  15. 15.854 − 798 =
  16. 16.744 − 599 =
  17. 17.921 − 239 =
  18. 18.942 − 797 =
  19. 19.957 − 499 =
  20. 20.717 − 697 =
  21. 21.313 − 298 =
  22. 22.691 − 517 =
  23. 23.858 − 299 =
  24. 24.791 − 608 =
  25. 25.409 − 297 =
  26. 26.357 − 197 =
  27. 27.923 − 699 =
  28. 28.960 − 608 =
  29. 29.751 − 589 =
  30. 30.507 − 399 =
  31. 31.727 − 499 =
  32. 32.747 − 398 =
  33. 33.913 − 697 =
  34. 34.751 − 398 =
  35. 35.945 − 498 =
  36. 36.898 − 797 =
  37. 37.571 − 409 =
  38. 38.963 − 197 =
  39. 39.596 − 329 =
  40. 40.861 − 669 =

Answer key

  1. 61
  2. 90
  3. 347
  4. 93
  5. 490
  6. 221
  7. 287
  8. 201
  9. 173
  10. 50
  11. 43
  12. 90
  13. 158
  14. 332
  15. 56
  16. 145
  17. 682
  18. 145
  19. 458
  20. 20
  21. 15
  22. 174
  23. 559
  24. 183
  25. 112
  26. 160
  27. 224
  28. 352
  29. 162
  30. 108
  31. 228
  32. 349
  33. 216
  34. 353
  35. 447
  36. 101
  37. 162
  38. 766
  39. 267
  40. 192

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