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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 807 · 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. 1.812 − 423 =
  2. 2.316 + 181 =
  3. 3.470 − 151 =
  4. 4.290 + 186 =
  5. 5.441 + 161 =
  6. 6.212 + 614 =
  7. 7.133 + 682 =
  8. 8.553 − 121 =
  9. 9.482 − 269 =
  10. 10.656 + 331 =
  11. 11.176 + 522 =
  12. 12.580 − 308 =
  13. 13.591 − 222 =
  14. 14.430 − 146 =
  15. 15.443 − 229 =
  16. 16.126 + 665 =
  17. 17.507 − 401 =
  18. 18.502 + 411 =
  19. 19.636 − 419 =
  20. 20.640 − 128 =
  21. 21.429 − 152 =
  22. 22.186 + 562 =
  23. 23.668 − 388 =
  24. 24.283 + 449 =
  25. 25.526 + 266 =
  26. 26.878 − 764 =
  27. 27.454 − 354 =
  28. 28.885 − 359 =
  29. 29.904 − 316 =
  30. 30.762 + 616 =
  31. 31.484 − 157 =
  32. 32.759 + 294 =
  33. 33.327 + 514 =
  34. 34.408 + 352 =
  35. 35.221 + 621 =
  36. 36.795 − 121 =
  37. 37.456 − 356 =
  38. 38.330 + 605 =
  39. 39.817 − 253 =
  40. 40.476 + 191 =

Answer key

  1. 389
  2. 497
  3. 319
  4. 476
  5. 602
  6. 826
  7. 815
  8. 432
  9. 213
  10. 987
  11. 698
  12. 272
  13. 369
  14. 284
  15. 214
  16. 791
  17. 106
  18. 913
  19. 217
  20. 512
  21. 277
  22. 748
  23. 280
  24. 732
  25. 792
  26. 114
  27. 100
  28. 526
  29. 588
  30. 1378
  31. 327
  32. 1053
  33. 841
  34. 760
  35. 842
  36. 674
  37. 100
  38. 935
  39. 564
  40. 667

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