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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 334 · 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. 1.954 − 361 =
  2. 2.317 + 331 =
  3. 3.177 + 255 =
  4. 4.472 + 118 =
  5. 5.670 − 493 =
  6. 6.427 + 551 =
  7. 7.529 − 171 =
  8. 8.452 + 183 =
  9. 9.573 − 331 =
  10. 10.295 + 234 =
  11. 11.918 − 374 =
  12. 12.472 − 136 =
  13. 13.398 + 406 =
  14. 14.732 + 178 =
  15. 15.564 − 431 =
  16. 16.455 + 231 =
  17. 17.623 + 141 =
  18. 18.760 − 172 =
  19. 19.478 + 232 =
  20. 20.271 + 361 =
  21. 21.154 + 521 =
  22. 22.746 − 614 =
  23. 23.450 − 314 =
  24. 24.584 + 161 =
  25. 25.457 + 359 =
  26. 26.547 − 321 =
  27. 27.670 + 184 =
  28. 28.255 + 267 =
  29. 29.406 + 616 =
  30. 30.696 + 519 =
  31. 31.664 − 378 =
  32. 32.595 + 241 =
  33. 33.689 + 225 =
  34. 34.295 + 339 =
  35. 35.728 + 687 =
  36. 36.331 + 204 =
  37. 37.140 + 417 =
  38. 38.849 − 746 =
  39. 39.577 − 169 =
  40. 40.714 − 503 =

Answer key

  1. 593
  2. 648
  3. 432
  4. 590
  5. 177
  6. 978
  7. 358
  8. 635
  9. 242
  10. 529
  11. 544
  12. 336
  13. 804
  14. 910
  15. 133
  16. 686
  17. 764
  18. 588
  19. 710
  20. 632
  21. 675
  22. 132
  23. 136
  24. 745
  25. 816
  26. 226
  27. 854
  28. 522
  29. 1022
  30. 1215
  31. 286
  32. 836
  33. 914
  34. 634
  35. 1415
  36. 535
  37. 557
  38. 103
  39. 408
  40. 211

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