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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 289 · 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. 1.278 + 683 =
  2. 2.281 + 144 =
  3. 3.409 + 274 =
  4. 4.735 + 271 =
  5. 5.593 + 461 =
  6. 6.486 − 116 =
  7. 7.227 + 536 =
  8. 8.556 + 254 =
  9. 9.491 − 163 =
  10. 10.728 + 555 =
  11. 11.975 − 243 =
  12. 12.527 − 251 =
  13. 13.382 + 176 =
  14. 14.715 − 514 =
  15. 15.864 − 392 =
  16. 16.726 − 404 =
  17. 17.131 + 483 =
  18. 18.482 + 639 =
  19. 19.440 − 258 =
  20. 20.890 − 217 =
  21. 21.156 + 129 =
  22. 22.698 − 548 =
  23. 23.565 − 299 =
  24. 24.596 + 222 =
  25. 25.441 + 586 =
  26. 26.819 − 226 =
  27. 27.611 + 321 =
  28. 28.589 + 352 =
  29. 29.549 + 571 =
  30. 30.670 − 314 =
  31. 31.271 + 406 =
  32. 32.418 − 239 =
  33. 33.268 + 408 =
  34. 34.721 − 554 =
  35. 35.512 − 162 =
  36. 36.632 − 288 =
  37. 37.439 − 129 =
  38. 38.498 − 349 =
  39. 39.463 − 192 =
  40. 40.784 − 369 =

Answer key

  1. 961
  2. 425
  3. 683
  4. 1006
  5. 1054
  6. 370
  7. 763
  8. 810
  9. 328
  10. 1283
  11. 732
  12. 276
  13. 558
  14. 201
  15. 472
  16. 322
  17. 614
  18. 1121
  19. 182
  20. 673
  21. 285
  22. 150
  23. 266
  24. 818
  25. 1027
  26. 593
  27. 932
  28. 941
  29. 1120
  30. 356
  31. 677
  32. 179
  33. 676
  34. 167
  35. 350
  36. 344
  37. 310
  38. 149
  39. 271
  40. 415

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