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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 90 · 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. 1.856 − 404 =
  2. 2.560 − 431 =
  3. 3.835 − 518 =
  4. 4.948 − 775 =
  5. 5.332 + 594 =
  6. 6.197 + 617 =
  7. 7.330 + 453 =
  8. 8.507 − 389 =
  9. 9.728 − 247 =
  10. 10.775 + 381 =
  11. 11.653 − 173 =
  12. 12.552 + 511 =
  13. 13.587 + 248 =
  14. 14.666 + 471 =
  15. 15.274 + 625 =
  16. 16.388 + 512 =
  17. 17.830 − 172 =
  18. 18.776 + 137 =
  19. 19.667 − 286 =
  20. 20.198 + 313 =
  21. 21.615 + 298 =
  22. 22.467 − 124 =
  23. 23.673 − 191 =
  24. 24.518 + 417 =
  25. 25.572 − 133 =
  26. 26.214 + 386 =
  27. 27.572 + 183 =
  28. 28.132 + 252 =
  29. 29.525 − 277 =
  30. 30.611 + 154 =
  31. 31.509 − 178 =
  32. 32.666 − 295 =
  33. 33.285 + 247 =
  34. 34.648 − 196 =
  35. 35.471 + 641 =
  36. 36.595 − 186 =
  37. 37.770 − 493 =
  38. 38.702 − 241 =
  39. 39.797 − 215 =
  40. 40.584 + 491 =

Answer key

  1. 452
  2. 129
  3. 317
  4. 173
  5. 926
  6. 814
  7. 783
  8. 118
  9. 481
  10. 1156
  11. 480
  12. 1063
  13. 835
  14. 1137
  15. 899
  16. 900
  17. 658
  18. 913
  19. 381
  20. 511
  21. 913
  22. 343
  23. 482
  24. 935
  25. 439
  26. 600
  27. 755
  28. 384
  29. 248
  30. 765
  31. 331
  32. 371
  33. 532
  34. 452
  35. 1112
  36. 409
  37. 277
  38. 461
  39. 582
  40. 1075

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