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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 627 · 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. 1.913 − 403 =
  2. 2.320 + 502 =
  3. 3.582 + 288 =
  4. 4.897 − 152 =
  5. 5.444 − 127 =
  6. 6.614 − 284 =
  7. 7.142 + 461 =
  8. 8.581 + 269 =
  9. 9.788 − 463 =
  10. 10.412 − 261 =
  11. 11.809 − 365 =
  12. 12.532 − 394 =
  13. 13.573 − 126 =
  14. 14.267 + 398 =
  15. 15.309 + 451 =
  16. 16.478 − 246 =
  17. 17.646 + 179 =
  18. 18.200 + 579 =
  19. 19.618 + 125 =
  20. 20.196 + 538 =
  21. 21.544 + 532 =
  22. 22.751 + 654 =
  23. 23.338 + 463 =
  24. 24.449 + 232 =
  25. 25.227 + 348 =
  26. 26.832 − 276 =
  27. 27.273 + 168 =
  28. 28.734 + 341 =
  29. 29.636 − 396 =
  30. 30.459 − 158 =
  31. 31.386 + 406 =
  32. 32.205 + 344 =
  33. 33.687 + 174 =
  34. 34.432 − 311 =
  35. 35.262 + 374 =
  36. 36.882 − 581 =
  37. 37.722 + 457 =
  38. 38.514 + 261 =
  39. 39.977 − 506 =
  40. 40.831 − 551 =

Answer key

  1. 510
  2. 822
  3. 870
  4. 745
  5. 317
  6. 330
  7. 603
  8. 850
  9. 325
  10. 151
  11. 444
  12. 138
  13. 447
  14. 665
  15. 760
  16. 232
  17. 825
  18. 779
  19. 743
  20. 734
  21. 1076
  22. 1405
  23. 801
  24. 681
  25. 575
  26. 556
  27. 441
  28. 1075
  29. 240
  30. 301
  31. 792
  32. 549
  33. 861
  34. 121
  35. 636
  36. 301
  37. 1179
  38. 775
  39. 471
  40. 280

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