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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 975 · 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. 1.812 − 699 =
  2. 2.831 − 797 =
  3. 3.826 − 299 =
  4. 4.884 − 699 =
  5. 5.547 − 299 =
  6. 6.980 − 699 =
  7. 7.437 − 417 =
  8. 8.970 − 197 =
  9. 9.772 − 609 =
  10. 10.826 − 658 =
  11. 11.947 − 579 =
  12. 12.809 − 368 =
  13. 13.636 − 499 =
  14. 14.880 − 199 =
  15. 15.949 − 699 =
  16. 16.992 − 799 =
  17. 17.613 − 497 =
  18. 18.935 − 697 =
  19. 19.888 − 197 =
  20. 20.966 − 199 =
  21. 21.925 − 698 =
  22. 22.800 − 297 =
  23. 23.787 − 699 =
  24. 24.366 − 197 =
  25. 25.652 − 598 =
  26. 26.911 − 797 =
  27. 27.450 − 397 =
  28. 28.812 − 537 =
  29. 29.927 − 798 =
  30. 30.420 − 369 =
  31. 31.951 − 589 =
  32. 32.321 − 298 =
  33. 33.892 − 398 =
  34. 34.730 − 699 =
  35. 35.966 − 599 =
  36. 36.702 − 407 =
  37. 37.589 − 398 =
  38. 38.936 − 399 =
  39. 39.427 − 368 =
  40. 40.472 − 198 =

Answer key

  1. 113
  2. 34
  3. 527
  4. 185
  5. 248
  6. 281
  7. 20
  8. 773
  9. 163
  10. 168
  11. 368
  12. 441
  13. 137
  14. 681
  15. 250
  16. 193
  17. 116
  18. 238
  19. 691
  20. 767
  21. 227
  22. 503
  23. 88
  24. 169
  25. 54
  26. 114
  27. 53
  28. 275
  29. 129
  30. 51
  31. 362
  32. 23
  33. 494
  34. 31
  35. 367
  36. 295
  37. 191
  38. 537
  39. 59
  40. 274

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