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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 477 · 40 questions
TalentJR

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

NameDateTime takenScore ___ / 40
  1. 1.478 − 199 =
  2. 2.532 + 531 =
  3. 3.132 + 225 =
  4. 4.845 − 579 =
  5. 5.326 + 649 =
  6. 6.443 + 227 =
  7. 7.416 + 229 =
  8. 8.742 − 141 =
  9. 9.319 + 413 =
  10. 10.481 − 263 =
  11. 11.231 + 292 =
  12. 12.437 − 306 =
  13. 13.467 + 409 =
  14. 14.518 − 204 =
  15. 15.252 + 614 =
  16. 16.287 + 119 =
  17. 17.277 + 521 =
  18. 18.859 − 354 =
  19. 19.247 + 398 =
  20. 20.820 − 396 =
  21. 21.912 − 768 =
  22. 22.515 − 151 =
  23. 23.390 + 457 =
  24. 24.464 − 363 =
  25. 25.592 + 261 =
  26. 26.192 + 663 =
  27. 27.512 + 301 =
  28. 28.244 + 129 =
  29. 29.629 + 391 =
  30. 30.281 + 567 =
  31. 31.522 − 173 =
  32. 32.575 + 463 =
  33. 33.716 − 277 =
  34. 34.138 + 627 =
  35. 35.787 + 341 =
  36. 36.505 + 162 =
  37. 37.242 + 663 =
  38. 38.778 + 645 =
  39. 39.655 − 177 =
  40. 40.725 + 338 =

Answer key

  1. 279
  2. 1063
  3. 357
  4. 266
  5. 975
  6. 670
  7. 645
  8. 601
  9. 732
  10. 218
  11. 523
  12. 131
  13. 876
  14. 314
  15. 866
  16. 406
  17. 798
  18. 505
  19. 645
  20. 424
  21. 144
  22. 364
  23. 847
  24. 101
  25. 853
  26. 855
  27. 813
  28. 373
  29. 1020
  30. 848
  31. 349
  32. 1038
  33. 439
  34. 765
  35. 1128
  36. 667
  37. 905
  38. 1423
  39. 478
  40. 1063

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