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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 472 · 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. 1.171 + 285 =
  2. 2.681 − 438 =
  3. 3.736 − 551 =
  4. 4.855 − 531 =
  5. 5.573 + 509 =
  6. 6.848 − 168 =
  7. 7.980 − 214 =
  8. 8.403 + 414 =
  9. 9.817 − 427 =
  10. 10.721 − 566 =
  11. 11.615 + 549 =
  12. 12.601 − 257 =
  13. 13.709 + 128 =
  14. 14.908 − 495 =
  15. 15.190 + 235 =
  16. 16.160 + 126 =
  17. 17.647 + 458 =
  18. 18.278 + 305 =
  19. 19.692 + 145 =
  20. 20.554 − 215 =
  21. 21.412 + 205 =
  22. 22.753 + 291 =
  23. 23.261 + 472 =
  24. 24.588 − 272 =
  25. 25.398 + 136 =
  26. 26.152 + 519 =
  27. 27.623 + 555 =
  28. 28.198 + 438 =
  29. 29.543 + 535 =
  30. 30.748 − 237 =
  31. 31.592 − 151 =
  32. 32.742 + 198 =
  33. 33.477 − 328 =
  34. 34.874 − 199 =
  35. 35.553 + 207 =
  36. 36.491 − 261 =
  37. 37.727 + 675 =
  38. 38.306 + 142 =
  39. 39.463 − 286 =
  40. 40.563 + 286 =

Answer key

  1. 456
  2. 243
  3. 185
  4. 324
  5. 1082
  6. 680
  7. 766
  8. 817
  9. 390
  10. 155
  11. 1164
  12. 344
  13. 837
  14. 413
  15. 425
  16. 286
  17. 1105
  18. 583
  19. 837
  20. 339
  21. 617
  22. 1044
  23. 733
  24. 316
  25. 534
  26. 671
  27. 1178
  28. 636
  29. 1078
  30. 511
  31. 441
  32. 940
  33. 149
  34. 675
  35. 760
  36. 230
  37. 1402
  38. 448
  39. 177
  40. 849

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