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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 175 · 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. 1.577 + 537 =
  2. 2.341 + 482 =
  3. 3.851 − 718 =
  4. 4.958 − 675 =
  5. 5.793 − 429 =
  6. 6.789 − 266 =
  7. 7.431 − 272 =
  8. 8.521 + 188 =
  9. 9.964 − 277 =
  10. 10.770 + 531 =
  11. 11.167 + 569 =
  12. 12.604 − 235 =
  13. 13.157 + 299 =
  14. 14.529 + 641 =
  15. 15.440 + 281 =
  16. 16.400 + 521 =
  17. 17.172 + 422 =
  18. 18.588 + 378 =
  19. 19.204 + 621 =
  20. 20.913 − 501 =
  21. 21.431 − 122 =
  22. 22.505 + 601 =
  23. 23.616 − 209 =
  24. 24.529 − 428 =
  25. 25.428 + 463 =
  26. 26.211 + 511 =
  27. 27.660 + 671 =
  28. 28.308 + 411 =
  29. 29.607 − 237 =
  30. 30.448 + 456 =
  31. 31.508 − 229 =
  32. 32.428 − 176 =
  33. 33.550 − 252 =
  34. 34.548 − 448 =
  35. 35.755 + 281 =
  36. 36.516 + 234 =
  37. 37.797 − 401 =
  38. 38.499 + 404 =
  39. 39.771 + 522 =
  40. 40.881 − 371 =

Answer key

  1. 1114
  2. 823
  3. 133
  4. 283
  5. 364
  6. 523
  7. 159
  8. 709
  9. 687
  10. 1301
  11. 736
  12. 369
  13. 456
  14. 1170
  15. 721
  16. 921
  17. 594
  18. 966
  19. 825
  20. 412
  21. 309
  22. 1106
  23. 407
  24. 101
  25. 891
  26. 722
  27. 1331
  28. 719
  29. 370
  30. 904
  31. 279
  32. 252
  33. 298
  34. 100
  35. 1036
  36. 750
  37. 396
  38. 903
  39. 1293
  40. 510

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