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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 171 · 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. 1.961 − 411 =
  2. 2.130 + 561 =
  3. 3.906 − 229 =
  4. 4.566 − 323 =
  5. 5.656 − 511 =
  6. 6.809 − 241 =
  7. 7.938 − 748 =
  8. 8.686 + 278 =
  9. 9.393 + 371 =
  10. 10.458 + 428 =
  11. 11.619 + 274 =
  12. 12.677 + 661 =
  13. 13.343 + 529 =
  14. 14.333 + 369 =
  15. 15.847 − 236 =
  16. 16.661 + 631 =
  17. 17.416 + 165 =
  18. 18.207 + 267 =
  19. 19.563 + 138 =
  20. 20.673 + 163 =
  21. 21.416 − 214 =
  22. 22.501 + 626 =
  23. 23.562 − 215 =
  24. 24.604 + 463 =
  25. 25.602 − 483 =
  26. 26.556 + 497 =
  27. 27.945 − 542 =
  28. 28.719 + 485 =
  29. 29.218 + 338 =
  30. 30.443 + 224 =
  31. 31.621 − 413 =
  32. 32.796 − 254 =
  33. 33.207 + 177 =
  34. 34.515 − 186 =
  35. 35.869 − 591 =
  36. 36.565 + 341 =
  37. 37.746 + 313 =
  38. 38.879 − 267 =
  39. 39.916 − 417 =
  40. 40.828 − 167 =

Answer key

  1. 550
  2. 691
  3. 677
  4. 243
  5. 145
  6. 568
  7. 190
  8. 964
  9. 764
  10. 886
  11. 893
  12. 1338
  13. 872
  14. 702
  15. 611
  16. 1292
  17. 581
  18. 474
  19. 701
  20. 836
  21. 202
  22. 1127
  23. 347
  24. 1067
  25. 119
  26. 1053
  27. 403
  28. 1204
  29. 556
  30. 667
  31. 208
  32. 542
  33. 384
  34. 329
  35. 278
  36. 906
  37. 1059
  38. 612
  39. 499
  40. 661

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