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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 862 · 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. 1.571 − 457 =
  2. 2.345 + 242 =
  3. 3.675 − 119 =
  4. 4.575 − 302 =
  5. 5.352 + 616 =
  6. 6.207 + 371 =
  7. 7.790 − 266 =
  8. 8.239 + 304 =
  9. 9.496 − 221 =
  10. 10.477 + 441 =
  11. 11.180 + 298 =
  12. 12.133 + 331 =
  13. 13.474 + 122 =
  14. 14.526 + 329 =
  15. 15.615 − 131 =
  16. 16.576 + 127 =
  17. 17.847 − 511 =
  18. 18.256 + 371 =
  19. 19.415 + 574 =
  20. 20.212 + 353 =
  21. 21.734 − 288 =
  22. 22.727 − 411 =
  23. 23.191 + 567 =
  24. 24.218 + 549 =
  25. 25.866 − 658 =
  26. 26.444 − 197 =
  27. 27.534 − 121 =
  28. 28.580 + 528 =
  29. 29.503 − 391 =
  30. 30.733 − 573 =
  31. 31.522 + 206 =
  32. 32.697 − 368 =
  33. 33.143 + 163 =
  34. 34.620 − 483 =
  35. 35.402 + 196 =
  36. 36.661 − 221 =
  37. 37.545 + 186 =
  38. 38.555 − 421 =
  39. 39.967 − 321 =
  40. 40.466 + 681 =

Answer key

  1. 114
  2. 587
  3. 556
  4. 273
  5. 968
  6. 578
  7. 524
  8. 543
  9. 275
  10. 918
  11. 478
  12. 464
  13. 596
  14. 855
  15. 484
  16. 703
  17. 336
  18. 627
  19. 989
  20. 565
  21. 446
  22. 316
  23. 758
  24. 767
  25. 208
  26. 247
  27. 413
  28. 1108
  29. 112
  30. 160
  31. 728
  32. 329
  33. 306
  34. 137
  35. 598
  36. 440
  37. 731
  38. 134
  39. 646
  40. 1147

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