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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 452 · 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. 1.532 − 149 =
  2. 2.267 + 414 =
  3. 3.729 − 128 =
  4. 4.908 − 748 =
  5. 5.603 + 484 =
  6. 6.681 − 463 =
  7. 7.482 + 169 =
  8. 8.367 + 231 =
  9. 9.880 − 622 =
  10. 10.590 − 145 =
  11. 11.750 + 333 =
  12. 12.970 − 436 =
  13. 13.707 + 463 =
  14. 14.872 − 234 =
  15. 15.440 + 215 =
  16. 16.528 − 324 =
  17. 17.653 + 261 =
  18. 18.249 + 305 =
  19. 19.376 + 123 =
  20. 20.643 + 208 =
  21. 21.687 + 234 =
  22. 22.324 + 356 =
  23. 23.651 − 261 =
  24. 24.802 − 486 =
  25. 25.562 − 281 =
  26. 26.720 + 233 =
  27. 27.957 − 315 =
  28. 28.400 + 406 =
  29. 29.507 + 438 =
  30. 30.379 + 302 =
  31. 31.444 + 544 =
  32. 32.750 − 601 =
  33. 33.493 − 278 =
  34. 34.407 + 515 =
  35. 35.807 − 435 =
  36. 36.147 + 197 =
  37. 37.471 + 262 =
  38. 38.486 − 113 =
  39. 39.190 + 303 =
  40. 40.181 + 216 =

Answer key

  1. 383
  2. 681
  3. 601
  4. 160
  5. 1087
  6. 218
  7. 651
  8. 598
  9. 258
  10. 445
  11. 1083
  12. 534
  13. 1170
  14. 638
  15. 655
  16. 204
  17. 914
  18. 554
  19. 499
  20. 851
  21. 921
  22. 680
  23. 390
  24. 316
  25. 281
  26. 953
  27. 642
  28. 806
  29. 945
  30. 681
  31. 988
  32. 149
  33. 215
  34. 922
  35. 372
  36. 344
  37. 733
  38. 373
  39. 493
  40. 397

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