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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 604 · 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. 1.972 − 181 =
  2. 2.438 + 597 =
  3. 3.728 − 321 =
  4. 4.781 − 657 =
  5. 5.466 + 133 =
  6. 6.462 − 313 =
  7. 7.673 − 396 =
  8. 8.624 + 597 =
  9. 9.435 − 329 =
  10. 10.178 + 595 =
  11. 11.493 − 213 =
  12. 12.125 + 351 =
  13. 13.325 + 411 =
  14. 14.711 − 229 =
  15. 15.374 + 643 =
  16. 16.235 + 448 =
  17. 17.869 − 301 =
  18. 18.433 + 485 =
  19. 19.195 + 606 =
  20. 20.587 + 141 =
  21. 21.248 + 394 =
  22. 22.634 + 387 =
  23. 23.776 + 467 =
  24. 24.748 − 561 =
  25. 25.782 − 588 =
  26. 26.502 + 562 =
  27. 27.895 − 699 =
  28. 28.807 − 591 =
  29. 29.775 + 673 =
  30. 30.508 + 329 =
  31. 31.456 − 231 =
  32. 32.742 + 611 =
  33. 33.672 + 408 =
  34. 34.484 + 217 =
  35. 35.134 + 591 =
  36. 36.829 − 636 =
  37. 37.955 − 301 =
  38. 38.571 + 205 =
  39. 39.481 − 341 =
  40. 40.600 + 242 =

Answer key

  1. 791
  2. 1035
  3. 407
  4. 124
  5. 599
  6. 149
  7. 277
  8. 1221
  9. 106
  10. 773
  11. 280
  12. 476
  13. 736
  14. 482
  15. 1017
  16. 683
  17. 568
  18. 918
  19. 801
  20. 728
  21. 642
  22. 1021
  23. 1243
  24. 187
  25. 194
  26. 1064
  27. 196
  28. 216
  29. 1448
  30. 837
  31. 225
  32. 1353
  33. 1080
  34. 701
  35. 725
  36. 193
  37. 654
  38. 776
  39. 140
  40. 842

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