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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 413 · 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. 1.889 − 506 =
  2. 2.906 − 767 =
  3. 3.424 + 135 =
  4. 4.977 − 556 =
  5. 5.615 + 121 =
  6. 6.950 − 183 =
  7. 7.290 + 152 =
  8. 8.736 − 354 =
  9. 9.484 + 483 =
  10. 10.675 − 237 =
  11. 11.787 − 404 =
  12. 12.497 + 176 =
  13. 13.568 − 203 =
  14. 14.138 + 138 =
  15. 15.454 + 656 =
  16. 16.506 + 361 =
  17. 17.759 + 319 =
  18. 18.581 − 359 =
  19. 19.662 + 141 =
  20. 20.596 + 246 =
  21. 21.577 − 468 =
  22. 22.700 − 209 =
  23. 23.381 + 466 =
  24. 24.724 + 224 =
  25. 25.600 + 467 =
  26. 26.360 + 185 =
  27. 27.777 + 226 =
  28. 28.183 + 218 =
  29. 29.532 + 515 =
  30. 30.242 + 547 =
  31. 31.427 + 169 =
  32. 32.689 + 367 =
  33. 33.539 + 256 =
  34. 34.941 − 117 =
  35. 35.842 − 231 =
  36. 36.769 − 644 =
  37. 37.688 + 199 =
  38. 38.661 + 656 =
  39. 39.208 + 114 =
  40. 40.449 − 137 =

Answer key

  1. 383
  2. 139
  3. 559
  4. 421
  5. 736
  6. 767
  7. 442
  8. 382
  9. 967
  10. 438
  11. 383
  12. 673
  13. 365
  14. 276
  15. 1110
  16. 867
  17. 1078
  18. 222
  19. 803
  20. 842
  21. 109
  22. 491
  23. 847
  24. 948
  25. 1067
  26. 545
  27. 1003
  28. 401
  29. 1047
  30. 789
  31. 596
  32. 1056
  33. 795
  34. 824
  35. 611
  36. 125
  37. 887
  38. 1317
  39. 322
  40. 312

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