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Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 523 · 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. 1.229 − 199 =
  2. 2.913 − 637 =
  3. 3.274 − 209 =
  4. 4.730 − 697 =
  5. 5.925 − 467 =
  6. 6.820 − 199 =
  7. 7.716 − 597 =
  8. 8.551 − 277 =
  9. 9.765 − 657 =
  10. 10.703 − 318 =
  11. 11.878 − 199 =
  12. 12.852 − 799 =
  13. 13.832 − 599 =
  14. 14.864 − 597 =
  15. 15.896 − 798 =
  16. 16.864 − 258 =
  17. 17.989 − 798 =
  18. 18.271 − 199 =
  19. 19.460 − 399 =
  20. 20.759 − 497 =
  21. 21.505 − 207 =
  22. 22.959 − 798 =
  23. 23.560 − 399 =
  24. 24.974 − 239 =
  25. 25.775 − 697 =
  26. 26.832 − 649 =
  27. 27.754 − 407 =
  28. 28.869 − 499 =
  29. 29.815 − 208 =
  30. 30.868 − 657 =
  31. 31.852 − 499 =
  32. 32.909 − 519 =
  33. 33.970 − 138 =
  34. 34.773 − 699 =
  35. 35.744 − 199 =
  36. 36.550 − 357 =
  37. 37.414 − 398 =
  38. 38.852 − 698 =
  39. 39.671 − 379 =
  40. 40.644 − 388 =

Answer key

  1. 30
  2. 276
  3. 65
  4. 33
  5. 458
  6. 621
  7. 119
  8. 274
  9. 108
  10. 385
  11. 679
  12. 53
  13. 233
  14. 267
  15. 98
  16. 606
  17. 191
  18. 72
  19. 61
  20. 262
  21. 298
  22. 161
  23. 161
  24. 735
  25. 78
  26. 183
  27. 347
  28. 370
  29. 607
  30. 211
  31. 353
  32. 390
  33. 832
  34. 74
  35. 545
  36. 193
  37. 16
  38. 154
  39. 292
  40. 256

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