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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 483 · 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. 1.431 − 161 =
  2. 2.275 + 265 =
  3. 3.206 + 149 =
  4. 4.560 − 291 =
  5. 5.711 + 635 =
  6. 6.160 + 363 =
  7. 7.446 + 303 =
  8. 8.479 + 512 =
  9. 9.882 − 511 =
  10. 10.462 + 477 =
  11. 11.834 − 604 =
  12. 12.358 + 393 =
  13. 13.211 + 238 =
  14. 14.450 − 286 =
  15. 15.368 + 391 =
  16. 16.546 + 536 =
  17. 17.131 + 271 =
  18. 18.485 − 301 =
  19. 19.576 + 432 =
  20. 20.839 − 518 =
  21. 21.247 + 563 =
  22. 22.475 + 323 =
  23. 23.471 + 397 =
  24. 24.179 + 152 =
  25. 25.152 + 287 =
  26. 26.165 + 614 =
  27. 27.663 − 478 =
  28. 28.478 + 493 =
  29. 29.796 − 571 =
  30. 30.675 − 425 =
  31. 31.757 + 548 =
  32. 32.671 + 136 =
  33. 33.889 − 351 =
  34. 34.714 − 351 =
  35. 35.387 + 199 =
  36. 36.832 − 414 =
  37. 37.199 + 429 =
  38. 38.577 + 198 =
  39. 39.738 + 648 =
  40. 40.664 + 531 =

Answer key

  1. 270
  2. 540
  3. 355
  4. 269
  5. 1346
  6. 523
  7. 749
  8. 991
  9. 371
  10. 939
  11. 230
  12. 751
  13. 449
  14. 164
  15. 759
  16. 1082
  17. 402
  18. 184
  19. 1008
  20. 321
  21. 810
  22. 798
  23. 868
  24. 331
  25. 439
  26. 779
  27. 185
  28. 971
  29. 225
  30. 250
  31. 1305
  32. 807
  33. 538
  34. 363
  35. 586
  36. 418
  37. 628
  38. 775
  39. 1386
  40. 1195

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