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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 113 · 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. 1.685 − 378 =
  2. 2.643 − 348 =
  3. 3.637 + 429 =
  4. 4.756 + 566 =
  5. 5.276 + 221 =
  6. 6.682 + 574 =
  7. 7.626 + 466 =
  8. 8.479 + 413 =
  9. 9.927 − 438 =
  10. 10.450 − 153 =
  11. 11.661 − 337 =
  12. 12.803 − 581 =
  13. 13.272 + 211 =
  14. 14.655 + 403 =
  15. 15.756 − 358 =
  16. 16.661 − 521 =
  17. 17.834 − 284 =
  18. 18.884 − 121 =
  19. 19.520 − 232 =
  20. 20.298 + 191 =
  21. 21.646 − 133 =
  22. 22.673 + 642 =
  23. 23.530 + 167 =
  24. 24.667 − 289 =
  25. 25.356 + 501 =
  26. 26.123 + 587 =
  27. 27.708 + 379 =
  28. 28.728 + 168 =
  29. 29.806 − 669 =
  30. 30.387 + 297 =
  31. 31.138 + 461 =
  32. 32.813 − 682 =
  33. 33.589 + 382 =
  34. 34.633 − 257 =
  35. 35.370 + 183 =
  36. 36.411 + 493 =
  37. 37.763 − 621 =
  38. 38.374 + 224 =
  39. 39.428 + 426 =
  40. 40.556 + 233 =

Answer key

  1. 307
  2. 295
  3. 1066
  4. 1322
  5. 497
  6. 1256
  7. 1092
  8. 892
  9. 489
  10. 297
  11. 324
  12. 222
  13. 483
  14. 1058
  15. 398
  16. 140
  17. 550
  18. 763
  19. 288
  20. 489
  21. 513
  22. 1315
  23. 697
  24. 378
  25. 857
  26. 710
  27. 1087
  28. 896
  29. 137
  30. 684
  31. 599
  32. 131
  33. 971
  34. 376
  35. 553
  36. 904
  37. 142
  38. 598
  39. 854
  40. 789

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