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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 790 · 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. 1.879 − 159 =
  2. 2.166 + 533 =
  3. 3.804 − 151 =
  4. 4.629 − 228 =
  5. 5.575 − 326 =
  6. 6.468 − 238 =
  7. 7.154 + 268 =
  8. 8.911 − 387 =
  9. 9.786 + 525 =
  10. 10.246 + 452 =
  11. 11.854 − 714 =
  12. 12.727 + 169 =
  13. 13.182 + 157 =
  14. 14.488 − 362 =
  15. 15.193 + 552 =
  16. 16.700 − 351 =
  17. 17.262 + 518 =
  18. 18.217 + 596 =
  19. 19.769 − 531 =
  20. 20.732 − 413 =
  21. 21.720 − 522 =
  22. 22.621 + 441 =
  23. 23.604 − 192 =
  24. 24.633 − 353 =
  25. 25.563 − 283 =
  26. 26.259 + 317 =
  27. 27.298 + 137 =
  28. 28.979 − 651 =
  29. 29.693 − 155 =
  30. 30.641 + 505 =
  31. 31.509 − 181 =
  32. 32.552 + 331 =
  33. 33.583 + 278 =
  34. 34.633 + 287 =
  35. 35.958 − 772 =
  36. 36.663 + 439 =
  37. 37.503 + 344 =
  38. 38.586 + 505 =
  39. 39.532 + 117 =
  40. 40.319 + 475 =

Answer key

  1. 720
  2. 699
  3. 653
  4. 401
  5. 249
  6. 230
  7. 422
  8. 524
  9. 1311
  10. 698
  11. 140
  12. 896
  13. 339
  14. 126
  15. 745
  16. 349
  17. 780
  18. 813
  19. 238
  20. 319
  21. 198
  22. 1062
  23. 412
  24. 280
  25. 280
  26. 576
  27. 435
  28. 328
  29. 538
  30. 1146
  31. 328
  32. 883
  33. 861
  34. 920
  35. 186
  36. 1102
  37. 847
  38. 1091
  39. 649
  40. 794

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