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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 899 · 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. 1.762 − 191 =
  2. 2.555 − 174 =
  3. 3.194 + 511 =
  4. 4.838 − 335 =
  5. 5.903 − 579 =
  6. 6.795 − 612 =
  7. 7.164 + 342 =
  8. 8.468 + 138 =
  9. 9.840 − 721 =
  10. 10.555 − 168 =
  11. 11.234 + 271 =
  12. 12.881 − 702 =
  13. 13.395 + 499 =
  14. 14.639 + 178 =
  15. 15.434 − 286 =
  16. 16.348 + 429 =
  17. 17.562 − 345 =
  18. 18.292 + 173 =
  19. 19.694 − 418 =
  20. 20.784 − 223 =
  21. 21.414 + 401 =
  22. 22.437 − 337 =
  23. 23.334 + 341 =
  24. 24.939 − 115 =
  25. 25.269 + 582 =
  26. 26.957 − 149 =
  27. 27.943 − 431 =
  28. 28.362 + 624 =
  29. 29.666 + 418 =
  30. 30.643 + 631 =
  31. 31.614 − 276 =
  32. 32.298 + 587 =
  33. 33.233 + 142 =
  34. 34.335 + 454 =
  35. 35.680 − 522 =
  36. 36.818 − 569 =
  37. 37.872 − 137 =
  38. 38.459 + 551 =
  39. 39.616 + 656 =
  40. 40.671 + 142 =

Answer key

  1. 571
  2. 381
  3. 705
  4. 503
  5. 324
  6. 183
  7. 506
  8. 606
  9. 119
  10. 387
  11. 505
  12. 179
  13. 894
  14. 817
  15. 148
  16. 777
  17. 217
  18. 465
  19. 276
  20. 561
  21. 815
  22. 100
  23. 675
  24. 824
  25. 851
  26. 808
  27. 512
  28. 986
  29. 1084
  30. 1274
  31. 338
  32. 885
  33. 375
  34. 789
  35. 158
  36. 249
  37. 735
  38. 1010
  39. 1272
  40. 813

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