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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 330 · 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. 1.179 + 647 =
  2. 2.442 − 264 =
  3. 3.479 − 195 =
  4. 4.753 + 521 =
  5. 5.577 − 237 =
  6. 6.686 + 621 =
  7. 7.219 + 129 =
  8. 8.878 − 491 =
  9. 9.372 + 607 =
  10. 10.646 + 136 =
  11. 11.974 − 113 =
  12. 12.830 − 657 =
  13. 13.563 − 356 =
  14. 14.276 + 597 =
  15. 15.314 + 574 =
  16. 16.878 − 257 =
  17. 17.462 + 194 =
  18. 18.881 − 363 =
  19. 19.545 + 272 =
  20. 20.216 + 251 =
  21. 21.436 − 134 =
  22. 22.710 + 631 =
  23. 23.501 + 429 =
  24. 24.416 + 623 =
  25. 25.657 − 195 =
  26. 26.439 + 131 =
  27. 27.448 + 596 =
  28. 28.463 + 241 =
  29. 29.469 − 208 =
  30. 30.293 + 652 =
  31. 31.555 − 324 =
  32. 32.737 + 469 =
  33. 33.496 − 288 =
  34. 34.749 − 279 =
  35. 35.882 − 226 =
  36. 36.200 + 542 =
  37. 37.769 + 314 =
  38. 38.198 + 331 =
  39. 39.185 + 398 =
  40. 40.614 + 676 =

Answer key

  1. 826
  2. 178
  3. 284
  4. 1274
  5. 340
  6. 1307
  7. 348
  8. 387
  9. 979
  10. 782
  11. 861
  12. 173
  13. 207
  14. 873
  15. 888
  16. 621
  17. 656
  18. 518
  19. 817
  20. 467
  21. 302
  22. 1341
  23. 930
  24. 1039
  25. 462
  26. 570
  27. 1044
  28. 704
  29. 261
  30. 945
  31. 231
  32. 1206
  33. 208
  34. 470
  35. 656
  36. 742
  37. 1083
  38. 529
  39. 583
  40. 1290

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