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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 908 · 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. 1.183 + 682 =
  2. 2.743 − 164 =
  3. 3.439 − 328 =
  4. 4.438 + 366 =
  5. 5.294 + 521 =
  6. 6.361 + 636 =
  7. 7.368 + 681 =
  8. 8.751 − 423 =
  9. 9.758 − 292 =
  10. 10.492 − 375 =
  11. 11.326 + 239 =
  12. 12.364 + 173 =
  13. 13.476 + 569 =
  14. 14.753 + 443 =
  15. 15.618 + 271 =
  16. 16.511 − 377 =
  17. 17.415 − 288 =
  18. 18.895 − 469 =
  19. 19.568 − 457 =
  20. 20.452 − 324 =
  21. 21.572 + 314 =
  22. 22.299 + 477 =
  23. 23.264 + 605 =
  24. 24.447 − 181 =
  25. 25.423 − 163 =
  26. 26.287 + 136 =
  27. 27.889 − 573 =
  28. 28.626 − 131 =
  29. 29.773 + 132 =
  30. 30.425 + 601 =
  31. 31.718 + 599 =
  32. 32.678 − 239 =
  33. 33.761 − 214 =
  34. 34.603 + 443 =
  35. 35.408 + 389 =
  36. 36.548 + 329 =
  37. 37.543 + 218 =
  38. 38.411 + 614 =
  39. 39.697 + 236 =
  40. 40.528 − 372 =

Answer key

  1. 865
  2. 579
  3. 111
  4. 804
  5. 815
  6. 997
  7. 1049
  8. 328
  9. 466
  10. 117
  11. 565
  12. 537
  13. 1045
  14. 1196
  15. 889
  16. 134
  17. 127
  18. 426
  19. 111
  20. 128
  21. 886
  22. 776
  23. 869
  24. 266
  25. 260
  26. 423
  27. 316
  28. 495
  29. 905
  30. 1026
  31. 1317
  32. 439
  33. 547
  34. 1046
  35. 797
  36. 877
  37. 761
  38. 1025
  39. 933
  40. 156

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