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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 800 · 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. 1.752 − 143 =
  2. 2.524 + 263 =
  3. 3.694 + 631 =
  4. 4.426 + 386 =
  5. 5.333 + 168 =
  6. 6.613 − 123 =
  7. 7.913 − 264 =
  8. 8.305 + 168 =
  9. 9.383 + 119 =
  10. 10.975 − 153 =
  11. 11.126 + 482 =
  12. 12.385 + 439 =
  13. 13.788 + 408 =
  14. 14.649 + 333 =
  15. 15.679 + 263 =
  16. 16.920 − 231 =
  17. 17.893 − 364 =
  18. 18.535 + 345 =
  19. 19.577 + 418 =
  20. 20.601 − 485 =
  21. 21.516 + 171 =
  22. 22.561 − 172 =
  23. 23.704 − 425 =
  24. 24.194 + 203 =
  25. 25.431 − 287 =
  26. 26.581 − 396 =
  27. 27.360 + 557 =
  28. 28.630 − 479 =
  29. 29.533 + 591 =
  30. 30.451 − 262 =
  31. 31.674 + 302 =
  32. 32.462 − 322 =
  33. 33.850 − 749 =
  34. 34.911 − 284 =
  35. 35.287 + 142 =
  36. 36.634 + 341 =
  37. 37.416 − 139 =
  38. 38.439 − 196 =
  39. 39.616 − 449 =
  40. 40.626 + 516 =

Answer key

  1. 609
  2. 787
  3. 1325
  4. 812
  5. 501
  6. 490
  7. 649
  8. 473
  9. 502
  10. 822
  11. 608
  12. 824
  13. 1196
  14. 982
  15. 942
  16. 689
  17. 529
  18. 880
  19. 995
  20. 116
  21. 687
  22. 389
  23. 279
  24. 397
  25. 144
  26. 185
  27. 917
  28. 151
  29. 1124
  30. 189
  31. 976
  32. 140
  33. 101
  34. 627
  35. 429
  36. 975
  37. 277
  38. 243
  39. 167
  40. 1142

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