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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 405 · 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. 1.621 − 432 =
  2. 2.143 + 214 =
  3. 3.747 + 179 =
  4. 4.370 + 487 =
  5. 5.817 − 267 =
  6. 6.717 + 376 =
  7. 7.450 + 271 =
  8. 8.561 + 648 =
  9. 9.214 + 584 =
  10. 10.485 + 348 =
  11. 11.607 + 198 =
  12. 12.637 + 476 =
  13. 13.916 − 403 =
  14. 14.630 + 176 =
  15. 15.538 + 434 =
  16. 16.561 − 158 =
  17. 17.623 + 631 =
  18. 18.517 − 146 =
  19. 19.495 − 301 =
  20. 20.681 + 242 =
  21. 21.807 − 632 =
  22. 22.444 − 121 =
  23. 23.670 − 143 =
  24. 24.504 + 481 =
  25. 25.266 + 521 =
  26. 26.539 + 625 =
  27. 27.207 + 268 =
  28. 28.473 − 247 =
  29. 29.306 + 231 =
  30. 30.905 − 417 =
  31. 31.377 + 499 =
  32. 32.968 − 258 =
  33. 33.344 + 358 =
  34. 34.588 − 125 =
  35. 35.283 + 635 =
  36. 36.537 − 294 =
  37. 37.936 − 217 =
  38. 38.487 − 218 =
  39. 39.565 − 418 =
  40. 40.666 − 153 =

Answer key

  1. 189
  2. 357
  3. 926
  4. 857
  5. 550
  6. 1093
  7. 721
  8. 1209
  9. 798
  10. 833
  11. 805
  12. 1113
  13. 513
  14. 806
  15. 972
  16. 403
  17. 1254
  18. 371
  19. 194
  20. 923
  21. 175
  22. 323
  23. 527
  24. 985
  25. 787
  26. 1164
  27. 475
  28. 226
  29. 537
  30. 488
  31. 876
  32. 710
  33. 702
  34. 463
  35. 918
  36. 243
  37. 719
  38. 269
  39. 147
  40. 513

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