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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 229 · 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. 1.467 + 207 =
  2. 2.742 − 505 =
  3. 3.163 + 569 =
  4. 4.534 − 318 =
  5. 5.449 + 466 =
  6. 6.348 + 401 =
  7. 7.314 + 344 =
  8. 8.710 − 326 =
  9. 9.901 − 636 =
  10. 10.963 − 705 =
  11. 11.537 + 191 =
  12. 12.683 − 116 =
  13. 13.564 + 287 =
  14. 14.442 − 278 =
  15. 15.428 − 199 =
  16. 16.617 − 387 =
  17. 17.353 + 184 =
  18. 18.560 + 127 =
  19. 19.587 + 143 =
  20. 20.615 − 193 =
  21. 21.194 + 241 =
  22. 22.366 + 534 =
  23. 23.411 + 605 =
  24. 24.569 − 208 =
  25. 25.518 − 207 =
  26. 26.506 − 156 =
  27. 27.577 + 661 =
  28. 28.701 + 142 =
  29. 29.154 + 391 =
  30. 30.712 + 571 =
  31. 31.400 + 496 =
  32. 32.750 − 519 =
  33. 33.661 + 549 =
  34. 34.795 − 294 =
  35. 35.714 + 516 =
  36. 36.866 − 759 =
  37. 37.233 + 614 =
  38. 38.610 + 612 =
  39. 39.305 + 336 =
  40. 40.602 + 276 =

Answer key

  1. 674
  2. 237
  3. 732
  4. 216
  5. 915
  6. 749
  7. 658
  8. 384
  9. 265
  10. 258
  11. 728
  12. 567
  13. 851
  14. 164
  15. 229
  16. 230
  17. 537
  18. 687
  19. 730
  20. 422
  21. 435
  22. 900
  23. 1016
  24. 361
  25. 311
  26. 350
  27. 1238
  28. 843
  29. 545
  30. 1283
  31. 896
  32. 231
  33. 1210
  34. 501
  35. 1230
  36. 107
  37. 847
  38. 1222
  39. 641
  40. 878

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