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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 935 · 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. 1.822 − 564 =
  2. 2.672 + 178 =
  3. 3.931 − 827 =
  4. 4.438 + 513 =
  5. 5.228 + 204 =
  6. 6.499 + 453 =
  7. 7.237 + 598 =
  8. 8.656 − 187 =
  9. 9.768 − 241 =
  10. 10.503 − 353 =
  11. 11.527 − 221 =
  12. 12.473 + 274 =
  13. 13.901 − 186 =
  14. 14.467 − 222 =
  15. 15.187 + 628 =
  16. 16.520 + 167 =
  17. 17.472 − 181 =
  18. 18.640 + 179 =
  19. 19.480 + 227 =
  20. 20.474 − 125 =
  21. 21.537 + 201 =
  22. 22.432 + 191 =
  23. 23.947 − 246 =
  24. 24.729 + 284 =
  25. 25.560 + 275 =
  26. 26.677 − 505 =
  27. 27.831 − 702 =
  28. 28.573 − 278 =
  29. 29.596 − 246 =
  30. 30.498 + 495 =
  31. 31.536 + 653 =
  32. 32.777 − 288 =
  33. 33.762 + 656 =
  34. 34.147 + 357 =
  35. 35.302 + 641 =
  36. 36.262 + 624 =
  37. 37.803 − 398 =
  38. 38.509 − 317 =
  39. 39.178 + 369 =
  40. 40.172 + 392 =

Answer key

  1. 258
  2. 850
  3. 104
  4. 951
  5. 432
  6. 952
  7. 835
  8. 469
  9. 527
  10. 150
  11. 306
  12. 747
  13. 715
  14. 245
  15. 815
  16. 687
  17. 291
  18. 819
  19. 707
  20. 349
  21. 738
  22. 623
  23. 701
  24. 1013
  25. 835
  26. 172
  27. 129
  28. 295
  29. 350
  30. 993
  31. 1189
  32. 489
  33. 1418
  34. 504
  35. 943
  36. 886
  37. 405
  38. 192
  39. 547
  40. 564

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