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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 649 · 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. 1.701 − 197 =
  2. 2.835 − 715 =
  3. 3.739 + 537 =
  4. 4.559 − 396 =
  5. 5.495 − 153 =
  6. 6.592 + 286 =
  7. 7.232 + 294 =
  8. 8.719 − 348 =
  9. 9.573 − 123 =
  10. 10.374 + 251 =
  11. 11.296 + 567 =
  12. 12.645 − 224 =
  13. 13.503 − 196 =
  14. 14.421 + 296 =
  15. 15.408 + 636 =
  16. 16.455 − 141 =
  17. 17.514 − 113 =
  18. 18.675 + 217 =
  19. 19.525 − 192 =
  20. 20.421 + 459 =
  21. 21.161 + 183 =
  22. 22.555 − 395 =
  23. 23.624 − 236 =
  24. 24.616 − 207 =
  25. 25.431 + 406 =
  26. 26.767 − 135 =
  27. 27.296 + 628 =
  28. 28.735 + 653 =
  29. 29.706 − 494 =
  30. 30.945 − 247 =
  31. 31.935 − 318 =
  32. 32.520 − 281 =
  33. 33.548 − 408 =
  34. 34.761 − 616 =
  35. 35.183 + 593 =
  36. 36.441 + 128 =
  37. 37.685 − 164 =
  38. 38.698 + 193 =
  39. 39.707 + 665 =
  40. 40.808 − 476 =

Answer key

  1. 504
  2. 120
  3. 1276
  4. 163
  5. 342
  6. 878
  7. 526
  8. 371
  9. 450
  10. 625
  11. 863
  12. 421
  13. 307
  14. 717
  15. 1044
  16. 314
  17. 401
  18. 892
  19. 333
  20. 880
  21. 344
  22. 160
  23. 388
  24. 409
  25. 837
  26. 632
  27. 924
  28. 1388
  29. 212
  30. 698
  31. 617
  32. 239
  33. 140
  34. 145
  35. 776
  36. 569
  37. 521
  38. 891
  39. 1372
  40. 332

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