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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 750 · 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. 1.611 + 444 =
  2. 2.476 + 204 =
  3. 3.850 − 588 =
  4. 4.904 − 246 =
  5. 5.574 − 398 =
  6. 6.491 − 376 =
  7. 7.538 − 435 =
  8. 8.862 − 359 =
  9. 9.927 − 582 =
  10. 10.454 − 298 =
  11. 11.863 − 112 =
  12. 12.328 + 398 =
  13. 13.885 − 176 =
  14. 14.563 − 331 =
  15. 15.549 − 281 =
  16. 16.685 − 446 =
  17. 17.523 + 586 =
  18. 18.666 + 208 =
  19. 19.522 + 139 =
  20. 20.259 + 681 =
  21. 21.543 − 193 =
  22. 22.861 − 244 =
  23. 23.653 − 185 =
  24. 24.674 − 528 =
  25. 25.676 − 338 =
  26. 26.621 − 317 =
  27. 27.307 + 676 =
  28. 28.437 − 171 =
  29. 29.735 + 351 =
  30. 30.915 − 621 =
  31. 31.190 + 343 =
  32. 32.486 + 461 =
  33. 33.724 + 113 =
  34. 34.292 + 384 =
  35. 35.428 + 273 =
  36. 36.984 − 582 =
  37. 37.907 − 149 =
  38. 38.365 + 461 =
  39. 39.317 + 536 =
  40. 40.140 + 226 =

Answer key

  1. 1055
  2. 680
  3. 262
  4. 658
  5. 176
  6. 115
  7. 103
  8. 503
  9. 345
  10. 156
  11. 751
  12. 726
  13. 709
  14. 232
  15. 268
  16. 239
  17. 1109
  18. 874
  19. 661
  20. 940
  21. 350
  22. 617
  23. 468
  24. 146
  25. 338
  26. 304
  27. 983
  28. 266
  29. 1086
  30. 294
  31. 533
  32. 947
  33. 837
  34. 676
  35. 701
  36. 402
  37. 758
  38. 826
  39. 853
  40. 366

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