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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 984 · 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. 1.206 + 411 =
  2. 2.573 + 554 =
  3. 3.290 + 214 =
  4. 4.265 + 342 =
  5. 5.734 + 222 =
  6. 6.313 + 322 =
  7. 7.532 + 577 =
  8. 8.551 + 342 =
  9. 9.929 − 192 =
  10. 10.849 − 283 =
  11. 11.465 − 137 =
  12. 12.589 + 499 =
  13. 13.864 − 421 =
  14. 14.477 − 192 =
  15. 15.425 + 174 =
  16. 16.382 + 677 =
  17. 17.810 − 484 =
  18. 18.682 − 279 =
  19. 19.638 − 415 =
  20. 20.443 + 145 =
  21. 21.142 + 328 =
  22. 22.641 − 331 =
  23. 23.614 − 245 =
  24. 24.535 − 294 =
  25. 25.190 + 178 =
  26. 26.239 + 113 =
  27. 27.359 + 418 =
  28. 28.522 + 469 =
  29. 29.546 − 133 =
  30. 30.792 − 461 =
  31. 31.555 + 599 =
  32. 32.634 − 521 =
  33. 33.637 − 182 =
  34. 34.969 − 723 =
  35. 35.561 − 222 =
  36. 36.596 − 186 =
  37. 37.927 − 265 =
  38. 38.815 − 468 =
  39. 39.606 − 224 =
  40. 40.772 + 288 =

Answer key

  1. 617
  2. 1127
  3. 504
  4. 607
  5. 956
  6. 635
  7. 1109
  8. 893
  9. 737
  10. 566
  11. 328
  12. 1088
  13. 443
  14. 285
  15. 599
  16. 1059
  17. 326
  18. 403
  19. 223
  20. 588
  21. 470
  22. 310
  23. 369
  24. 241
  25. 368
  26. 352
  27. 777
  28. 991
  29. 413
  30. 331
  31. 1154
  32. 113
  33. 455
  34. 246
  35. 339
  36. 410
  37. 662
  38. 347
  39. 382
  40. 1060

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