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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 248 · 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. 1.950 − 255 =
  2. 2.635 + 429 =
  3. 3.255 + 128 =
  4. 4.695 − 547 =
  5. 5.826 − 712 =
  6. 6.739 + 256 =
  7. 7.763 + 186 =
  8. 8.631 + 245 =
  9. 9.536 − 211 =
  10. 10.515 + 365 =
  11. 11.532 − 335 =
  12. 12.278 + 535 =
  13. 13.549 − 448 =
  14. 14.586 − 341 =
  15. 15.281 + 525 =
  16. 16.200 + 413 =
  17. 17.601 + 332 =
  18. 18.768 + 437 =
  19. 19.213 + 269 =
  20. 20.586 + 659 =
  21. 21.585 − 191 =
  22. 22.879 − 393 =
  23. 23.893 − 549 =
  24. 24.855 − 684 =
  25. 25.240 + 609 =
  26. 26.284 + 426 =
  27. 27.660 + 581 =
  28. 28.759 − 495 =
  29. 29.290 + 218 =
  30. 30.898 − 431 =
  31. 31.129 + 154 =
  32. 32.590 + 248 =
  33. 33.934 − 514 =
  34. 34.392 + 241 =
  35. 35.941 − 576 =
  36. 36.778 − 635 =
  37. 37.790 − 597 =
  38. 38.191 + 461 =
  39. 39.464 + 206 =
  40. 40.770 − 598 =

Answer key

  1. 695
  2. 1064
  3. 383
  4. 148
  5. 114
  6. 995
  7. 949
  8. 876
  9. 325
  10. 880
  11. 197
  12. 813
  13. 101
  14. 245
  15. 806
  16. 613
  17. 933
  18. 1205
  19. 482
  20. 1245
  21. 394
  22. 486
  23. 344
  24. 171
  25. 849
  26. 710
  27. 1241
  28. 264
  29. 508
  30. 467
  31. 283
  32. 838
  33. 420
  34. 633
  35. 365
  36. 143
  37. 193
  38. 652
  39. 670
  40. 172

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