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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 409 · 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. 1.250 + 273 =
  2. 2.696 + 425 =
  3. 3.800 − 511 =
  4. 4.237 + 216 =
  5. 5.500 + 465 =
  6. 6.627 + 151 =
  7. 7.427 − 313 =
  8. 8.308 + 622 =
  9. 9.742 − 545 =
  10. 10.608 + 141 =
  11. 11.785 + 551 =
  12. 12.638 − 484 =
  13. 13.437 + 571 =
  14. 14.466 + 574 =
  15. 15.651 + 249 =
  16. 16.587 + 426 =
  17. 17.460 + 533 =
  18. 18.504 + 528 =
  19. 19.563 − 367 =
  20. 20.471 + 383 =
  21. 21.229 + 254 =
  22. 22.813 − 142 =
  23. 23.640 + 226 =
  24. 24.516 + 398 =
  25. 25.787 − 321 =
  26. 26.540 + 139 =
  27. 27.986 − 761 =
  28. 28.612 − 131 =
  29. 29.215 + 588 =
  30. 30.423 + 602 =
  31. 31.282 + 361 =
  32. 32.733 − 495 =
  33. 33.474 + 501 =
  34. 34.574 + 408 =
  35. 35.976 − 215 =
  36. 36.260 + 659 =
  37. 37.534 + 427 =
  38. 38.619 + 189 =
  39. 39.723 + 173 =
  40. 40.564 − 206 =

Answer key

  1. 523
  2. 1121
  3. 289
  4. 453
  5. 965
  6. 778
  7. 114
  8. 930
  9. 197
  10. 749
  11. 1336
  12. 154
  13. 1008
  14. 1040
  15. 900
  16. 1013
  17. 993
  18. 1032
  19. 196
  20. 854
  21. 483
  22. 671
  23. 866
  24. 914
  25. 466
  26. 679
  27. 225
  28. 481
  29. 803
  30. 1025
  31. 643
  32. 238
  33. 975
  34. 982
  35. 761
  36. 919
  37. 961
  38. 808
  39. 896
  40. 358

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