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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 612 · 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. 1.560 − 406 =
  2. 2.525 + 203 =
  3. 3.603 + 241 =
  4. 4.298 + 322 =
  5. 5.930 − 727 =
  6. 6.775 − 523 =
  7. 7.237 + 386 =
  8. 8.812 − 429 =
  9. 9.144 + 303 =
  10. 10.528 − 141 =
  11. 11.190 + 545 =
  12. 12.668 + 323 =
  13. 13.949 − 668 =
  14. 14.206 + 661 =
  15. 15.421 − 306 =
  16. 16.130 + 645 =
  17. 17.457 + 418 =
  18. 18.344 + 426 =
  19. 19.890 − 551 =
  20. 20.537 − 411 =
  21. 21.419 + 119 =
  22. 22.538 + 414 =
  23. 23.282 + 232 =
  24. 24.826 − 405 =
  25. 25.902 − 519 =
  26. 26.957 − 207 =
  27. 27.430 − 282 =
  28. 28.563 − 121 =
  29. 29.520 + 197 =
  30. 30.691 − 529 =
  31. 31.491 + 436 =
  32. 32.704 − 125 =
  33. 33.834 − 682 =
  34. 34.774 − 336 =
  35. 35.545 + 467 =
  36. 36.607 − 461 =
  37. 37.425 + 351 =
  38. 38.606 + 676 =
  39. 39.484 + 347 =
  40. 40.714 − 466 =

Answer key

  1. 154
  2. 728
  3. 844
  4. 620
  5. 203
  6. 252
  7. 623
  8. 383
  9. 447
  10. 387
  11. 735
  12. 991
  13. 281
  14. 867
  15. 115
  16. 775
  17. 875
  18. 770
  19. 339
  20. 126
  21. 538
  22. 952
  23. 514
  24. 421
  25. 383
  26. 750
  27. 148
  28. 442
  29. 717
  30. 162
  31. 927
  32. 579
  33. 152
  34. 438
  35. 1012
  36. 146
  37. 776
  38. 1282
  39. 831
  40. 248

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