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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 524 · 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. 1.914 − 475 =
  2. 2.345 + 684 =
  3. 3.937 − 279 =
  4. 4.450 + 231 =
  5. 5.374 + 154 =
  6. 6.421 + 481 =
  7. 7.828 − 114 =
  8. 8.503 − 232 =
  9. 9.580 + 478 =
  10. 10.383 + 478 =
  11. 11.151 + 585 =
  12. 12.319 + 535 =
  13. 13.441 − 119 =
  14. 14.204 + 428 =
  15. 15.272 + 338 =
  16. 16.695 + 303 =
  17. 17.261 + 186 =
  18. 18.804 − 199 =
  19. 19.937 − 764 =
  20. 20.494 − 347 =
  21. 21.387 + 681 =
  22. 22.556 − 314 =
  23. 23.490 − 338 =
  24. 24.902 − 612 =
  25. 25.157 + 136 =
  26. 26.752 + 681 =
  27. 27.360 + 566 =
  28. 28.601 + 541 =
  29. 29.172 + 645 =
  30. 30.435 − 177 =
  31. 31.579 − 392 =
  32. 32.918 − 396 =
  33. 33.822 − 625 =
  34. 34.648 + 363 =
  35. 35.139 + 586 =
  36. 36.257 + 402 =
  37. 37.778 + 625 =
  38. 38.401 + 533 =
  39. 39.327 + 269 =
  40. 40.498 + 289 =

Answer key

  1. 439
  2. 1029
  3. 658
  4. 681
  5. 528
  6. 902
  7. 714
  8. 271
  9. 1058
  10. 861
  11. 736
  12. 854
  13. 322
  14. 632
  15. 610
  16. 998
  17. 447
  18. 605
  19. 173
  20. 147
  21. 1068
  22. 242
  23. 152
  24. 290
  25. 293
  26. 1433
  27. 926
  28. 1142
  29. 817
  30. 258
  31. 187
  32. 522
  33. 197
  34. 1011
  35. 725
  36. 659
  37. 1403
  38. 934
  39. 596
  40. 787

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