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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 268 · 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. 1.363 + 217 =
  2. 2.716 − 336 =
  3. 3.743 + 175 =
  4. 4.227 + 268 =
  5. 5.723 − 607 =
  6. 6.478 − 155 =
  7. 7.402 + 231 =
  8. 8.621 − 453 =
  9. 9.137 + 483 =
  10. 10.696 − 296 =
  11. 11.653 + 145 =
  12. 12.819 − 431 =
  13. 13.454 + 188 =
  14. 14.485 + 225 =
  15. 15.183 + 672 =
  16. 16.890 − 528 =
  17. 17.661 + 276 =
  18. 18.562 + 514 =
  19. 19.568 + 353 =
  20. 20.671 − 474 =
  21. 21.517 + 166 =
  22. 22.621 − 161 =
  23. 23.503 + 542 =
  24. 24.768 + 459 =
  25. 25.534 + 373 =
  26. 26.598 + 652 =
  27. 27.193 + 331 =
  28. 28.274 + 671 =
  29. 29.524 − 236 =
  30. 30.717 − 612 =
  31. 31.472 − 281 =
  32. 32.685 + 616 =
  33. 33.163 + 148 =
  34. 34.481 − 136 =
  35. 35.580 + 242 =
  36. 36.788 + 406 =
  37. 37.511 − 177 =
  38. 38.347 + 156 =
  39. 39.314 + 291 =
  40. 40.978 − 416 =

Answer key

  1. 580
  2. 380
  3. 918
  4. 495
  5. 116
  6. 323
  7. 633
  8. 168
  9. 620
  10. 400
  11. 798
  12. 388
  13. 642
  14. 710
  15. 855
  16. 362
  17. 937
  18. 1076
  19. 921
  20. 197
  21. 683
  22. 460
  23. 1045
  24. 1227
  25. 907
  26. 1250
  27. 524
  28. 945
  29. 288
  30. 105
  31. 191
  32. 1301
  33. 311
  34. 345
  35. 822
  36. 1194
  37. 334
  38. 503
  39. 605
  40. 562

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