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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 870 · 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. 1.492 − 319 =
  2. 2.984 − 247 =
  3. 3.637 + 423 =
  4. 4.440 + 592 =
  5. 5.206 + 367 =
  6. 6.292 + 204 =
  7. 7.189 + 416 =
  8. 8.884 − 288 =
  9. 9.707 − 541 =
  10. 10.422 + 577 =
  11. 11.727 + 116 =
  12. 12.481 − 313 =
  13. 13.906 − 466 =
  14. 14.975 − 735 =
  15. 15.673 − 298 =
  16. 16.678 + 473 =
  17. 17.219 + 224 =
  18. 18.847 − 733 =
  19. 19.503 − 196 =
  20. 20.659 + 176 =
  21. 21.277 + 627 =
  22. 22.212 + 229 =
  23. 23.729 − 417 =
  24. 24.654 + 589 =
  25. 25.665 − 506 =
  26. 26.280 + 632 =
  27. 27.741 − 161 =
  28. 28.515 + 638 =
  29. 29.448 − 271 =
  30. 30.329 + 236 =
  31. 31.574 − 241 =
  32. 32.299 + 123 =
  33. 33.859 − 566 =
  34. 34.603 + 433 =
  35. 35.139 + 405 =
  36. 36.986 − 151 =
  37. 37.730 + 612 =
  38. 38.504 + 228 =
  39. 39.545 + 637 =
  40. 40.324 + 255 =

Answer key

  1. 173
  2. 737
  3. 1060
  4. 1032
  5. 573
  6. 496
  7. 605
  8. 596
  9. 166
  10. 999
  11. 843
  12. 168
  13. 440
  14. 240
  15. 375
  16. 1151
  17. 443
  18. 114
  19. 307
  20. 835
  21. 904
  22. 441
  23. 312
  24. 1243
  25. 159
  26. 912
  27. 580
  28. 1153
  29. 177
  30. 565
  31. 333
  32. 422
  33. 293
  34. 1036
  35. 544
  36. 835
  37. 1342
  38. 732
  39. 1182
  40. 579

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