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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 123 · 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. 1.567 − 129 =
  2. 2.718 − 311 =
  3. 3.509 + 182 =
  4. 4.413 + 641 =
  5. 5.808 − 568 =
  6. 6.634 − 381 =
  7. 7.761 − 499 =
  8. 8.512 + 589 =
  9. 9.816 − 211 =
  10. 10.865 − 285 =
  11. 11.398 + 585 =
  12. 12.933 − 801 =
  13. 13.284 + 426 =
  14. 14.474 + 663 =
  15. 15.683 + 338 =
  16. 16.487 − 358 =
  17. 17.131 + 353 =
  18. 18.502 − 123 =
  19. 19.680 + 302 =
  20. 20.422 − 221 =
  21. 21.425 + 462 =
  22. 22.414 − 206 =
  23. 23.169 + 197 =
  24. 24.685 + 351 =
  25. 25.419 − 196 =
  26. 26.745 + 682 =
  27. 27.659 − 141 =
  28. 28.278 + 251 =
  29. 29.353 + 585 =
  30. 30.974 − 358 =
  31. 31.786 + 386 =
  32. 32.171 + 372 =
  33. 33.479 − 206 =
  34. 34.612 + 118 =
  35. 35.882 − 229 =
  36. 36.631 − 337 =
  37. 37.558 + 478 =
  38. 38.652 + 355 =
  39. 39.906 − 752 =
  40. 40.524 + 196 =

Answer key

  1. 438
  2. 407
  3. 691
  4. 1054
  5. 240
  6. 253
  7. 262
  8. 1101
  9. 605
  10. 580
  11. 983
  12. 132
  13. 710
  14. 1137
  15. 1021
  16. 129
  17. 484
  18. 379
  19. 982
  20. 201
  21. 887
  22. 208
  23. 366
  24. 1036
  25. 223
  26. 1427
  27. 518
  28. 529
  29. 938
  30. 616
  31. 1172
  32. 543
  33. 273
  34. 730
  35. 653
  36. 294
  37. 1036
  38. 1007
  39. 154
  40. 720

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