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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 781 · 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. 1.685 − 313 =
  2. 2.210 + 534 =
  3. 3.699 + 523 =
  4. 4.623 + 116 =
  5. 5.462 + 683 =
  6. 6.546 − 136 =
  7. 7.755 + 478 =
  8. 8.357 + 611 =
  9. 9.700 − 432 =
  10. 10.340 + 304 =
  11. 11.497 + 345 =
  12. 12.328 + 185 =
  13. 13.542 + 122 =
  14. 14.790 − 444 =
  15. 15.239 + 457 =
  16. 16.298 + 333 =
  17. 17.667 − 341 =
  18. 18.521 + 231 =
  19. 19.682 − 153 =
  20. 20.497 − 335 =
  21. 21.817 − 151 =
  22. 22.274 + 655 =
  23. 23.378 + 649 =
  24. 24.903 − 172 =
  25. 25.569 + 273 =
  26. 26.465 − 323 =
  27. 27.565 − 357 =
  28. 28.777 − 454 =
  29. 29.534 + 208 =
  30. 30.853 − 433 =
  31. 31.256 + 526 =
  32. 32.530 + 209 =
  33. 33.741 − 161 =
  34. 34.719 − 121 =
  35. 35.318 + 438 =
  36. 36.330 + 221 =
  37. 37.621 + 456 =
  38. 38.155 + 199 =
  39. 39.568 − 209 =
  40. 40.916 − 767 =

Answer key

  1. 372
  2. 744
  3. 1222
  4. 739
  5. 1145
  6. 410
  7. 1233
  8. 968
  9. 268
  10. 644
  11. 842
  12. 513
  13. 664
  14. 346
  15. 696
  16. 631
  17. 326
  18. 752
  19. 529
  20. 162
  21. 666
  22. 929
  23. 1027
  24. 731
  25. 842
  26. 142
  27. 208
  28. 323
  29. 742
  30. 420
  31. 782
  32. 739
  33. 580
  34. 598
  35. 756
  36. 551
  37. 1077
  38. 354
  39. 359
  40. 149

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