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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 94 · 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. 1.131 + 226 =
  2. 2.755 + 115 =
  3. 3.580 + 366 =
  4. 4.829 − 184 =
  5. 5.477 + 501 =
  6. 6.644 + 132 =
  7. 7.163 + 163 =
  8. 8.335 + 233 =
  9. 9.459 − 341 =
  10. 10.334 + 382 =
  11. 11.822 − 601 =
  12. 12.452 − 268 =
  13. 13.677 − 548 =
  14. 14.554 − 201 =
  15. 15.327 + 223 =
  16. 16.264 + 551 =
  17. 17.891 − 707 =
  18. 18.438 − 204 =
  19. 19.723 + 342 =
  20. 20.225 + 326 =
  21. 21.413 + 436 =
  22. 22.216 + 128 =
  23. 23.704 + 261 =
  24. 24.919 − 761 =
  25. 25.282 + 541 =
  26. 26.140 + 357 =
  27. 27.497 − 333 =
  28. 28.195 + 516 =
  29. 29.754 + 616 =
  30. 30.447 + 261 =
  31. 31.262 + 522 =
  32. 32.150 + 265 =
  33. 33.366 + 514 =
  34. 34.156 + 183 =
  35. 35.482 + 536 =
  36. 36.411 + 533 =
  37. 37.700 + 121 =
  38. 38.535 + 642 =
  39. 39.679 + 665 =
  40. 40.646 + 619 =

Answer key

  1. 357
  2. 870
  3. 946
  4. 645
  5. 978
  6. 776
  7. 326
  8. 568
  9. 118
  10. 716
  11. 221
  12. 184
  13. 129
  14. 353
  15. 550
  16. 815
  17. 184
  18. 234
  19. 1065
  20. 551
  21. 849
  22. 344
  23. 965
  24. 158
  25. 823
  26. 497
  27. 164
  28. 711
  29. 1370
  30. 708
  31. 784
  32. 415
  33. 880
  34. 339
  35. 1018
  36. 944
  37. 821
  38. 1177
  39. 1344
  40. 1265

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