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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 891 · 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. 1.244 + 658 =
  2. 2.577 + 598 =
  3. 3.573 − 368 =
  4. 4.409 + 193 =
  5. 5.425 + 561 =
  6. 6.579 + 579 =
  7. 7.953 − 458 =
  8. 8.146 + 521 =
  9. 9.763 − 173 =
  10. 10.260 + 123 =
  11. 11.456 + 668 =
  12. 12.909 − 376 =
  13. 13.175 + 453 =
  14. 14.306 + 244 =
  15. 15.218 + 412 =
  16. 16.299 + 139 =
  17. 17.374 + 125 =
  18. 18.300 + 678 =
  19. 19.471 − 118 =
  20. 20.295 + 326 =
  21. 21.149 + 676 =
  22. 22.710 − 132 =
  23. 23.767 + 294 =
  24. 24.943 − 765 =
  25. 25.260 + 201 =
  26. 26.562 + 151 =
  27. 27.804 − 672 =
  28. 28.922 − 139 =
  29. 29.766 − 174 =
  30. 30.622 − 474 =
  31. 31.225 + 158 =
  32. 32.300 + 217 =
  33. 33.460 − 306 =
  34. 34.649 + 661 =
  35. 35.542 − 189 =
  36. 36.797 − 281 =
  37. 37.421 − 158 =
  38. 38.603 + 342 =
  39. 39.544 + 645 =
  40. 40.290 + 623 =

Answer key

  1. 902
  2. 1175
  3. 205
  4. 602
  5. 986
  6. 1158
  7. 495
  8. 667
  9. 590
  10. 383
  11. 1124
  12. 533
  13. 628
  14. 550
  15. 630
  16. 438
  17. 499
  18. 978
  19. 353
  20. 621
  21. 825
  22. 578
  23. 1061
  24. 178
  25. 461
  26. 713
  27. 132
  28. 783
  29. 592
  30. 148
  31. 383
  32. 517
  33. 154
  34. 1310
  35. 353
  36. 516
  37. 263
  38. 945
  39. 1189
  40. 913

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