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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 657 · 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. 1.664 − 131 =
  2. 2.742 − 636 =
  3. 3.523 + 561 =
  4. 4.669 − 395 =
  5. 5.717 + 588 =
  6. 6.502 + 141 =
  7. 7.416 + 205 =
  8. 8.396 + 671 =
  9. 9.727 − 178 =
  10. 10.727 + 149 =
  11. 11.301 + 132 =
  12. 12.651 + 413 =
  13. 13.574 − 301 =
  14. 14.471 − 261 =
  15. 15.977 − 751 =
  16. 16.507 + 237 =
  17. 17.718 + 118 =
  18. 18.299 + 473 =
  19. 19.800 − 196 =
  20. 20.302 + 505 =
  21. 21.976 − 196 =
  22. 22.472 − 292 =
  23. 23.652 + 675 =
  24. 24.507 − 257 =
  25. 25.169 + 236 =
  26. 26.651 − 316 =
  27. 27.131 + 477 =
  28. 28.627 − 281 =
  29. 29.365 + 279 =
  30. 30.394 + 611 =
  31. 31.261 + 536 =
  32. 32.349 + 641 =
  33. 33.840 − 425 =
  34. 34.642 + 171 =
  35. 35.903 − 242 =
  36. 36.670 + 376 =
  37. 37.936 − 479 =
  38. 38.273 + 382 =
  39. 39.594 − 375 =
  40. 40.770 + 269 =

Answer key

  1. 533
  2. 106
  3. 1084
  4. 274
  5. 1305
  6. 643
  7. 621
  8. 1067
  9. 549
  10. 876
  11. 433
  12. 1064
  13. 273
  14. 210
  15. 226
  16. 744
  17. 836
  18. 772
  19. 604
  20. 807
  21. 780
  22. 180
  23. 1327
  24. 250
  25. 405
  26. 335
  27. 608
  28. 346
  29. 644
  30. 1005
  31. 797
  32. 990
  33. 415
  34. 813
  35. 661
  36. 1046
  37. 457
  38. 655
  39. 219
  40. 1039

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