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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 903 · 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. 1.579 − 244 =
  2. 2.550 − 231 =
  3. 3.200 + 491 =
  4. 4.884 − 344 =
  5. 5.691 − 476 =
  6. 6.756 − 198 =
  7. 7.502 + 465 =
  8. 8.976 − 336 =
  9. 9.265 + 394 =
  10. 10.691 − 163 =
  11. 11.612 − 468 =
  12. 12.679 − 454 =
  13. 13.672 − 516 =
  14. 14.883 − 721 =
  15. 15.650 − 234 =
  16. 16.532 + 371 =
  17. 17.683 + 381 =
  18. 18.558 − 213 =
  19. 19.643 + 219 =
  20. 20.859 − 698 =
  21. 21.476 − 116 =
  22. 22.540 + 508 =
  23. 23.360 + 338 =
  24. 24.954 − 613 =
  25. 25.653 + 661 =
  26. 26.545 − 133 =
  27. 27.188 + 278 =
  28. 28.711 − 431 =
  29. 29.530 − 168 =
  30. 30.888 − 243 =
  31. 31.320 + 224 =
  32. 32.171 + 127 =
  33. 33.495 + 132 =
  34. 34.773 − 392 =
  35. 35.577 + 625 =
  36. 36.330 + 151 =
  37. 37.260 + 219 =
  38. 38.547 − 362 =
  39. 39.778 − 169 =
  40. 40.494 − 382 =

Answer key

  1. 335
  2. 319
  3. 691
  4. 540
  5. 215
  6. 558
  7. 967
  8. 640
  9. 659
  10. 528
  11. 144
  12. 225
  13. 156
  14. 162
  15. 416
  16. 903
  17. 1064
  18. 345
  19. 862
  20. 161
  21. 360
  22. 1048
  23. 698
  24. 341
  25. 1314
  26. 412
  27. 466
  28. 280
  29. 362
  30. 645
  31. 544
  32. 298
  33. 627
  34. 381
  35. 1202
  36. 481
  37. 479
  38. 185
  39. 609
  40. 112

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