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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 444 · 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. 1.544 + 181 =
  2. 2.540 − 245 =
  3. 3.790 − 432 =
  4. 4.392 + 462 =
  5. 5.428 − 146 =
  6. 6.658 − 531 =
  7. 7.432 − 332 =
  8. 8.224 + 163 =
  9. 9.430 − 273 =
  10. 10.911 − 398 =
  11. 11.537 + 447 =
  12. 12.929 − 116 =
  13. 13.778 + 567 =
  14. 14.543 − 397 =
  15. 15.325 + 239 =
  16. 16.517 − 168 =
  17. 17.472 − 302 =
  18. 18.422 + 535 =
  19. 19.486 + 626 =
  20. 20.560 − 185 =
  21. 21.449 + 238 =
  22. 22.754 − 514 =
  23. 23.192 + 588 =
  24. 24.672 − 406 =
  25. 25.752 + 391 =
  26. 26.814 − 627 =
  27. 27.658 + 348 =
  28. 28.913 − 724 =
  29. 29.921 − 162 =
  30. 30.604 + 243 =
  31. 31.422 + 254 =
  32. 32.616 + 289 =
  33. 33.683 − 314 =
  34. 34.901 − 381 =
  35. 35.583 + 549 =
  36. 36.801 − 665 =
  37. 37.166 + 434 =
  38. 38.507 + 271 =
  39. 39.493 + 149 =
  40. 40.702 − 601 =

Answer key

  1. 725
  2. 295
  3. 358
  4. 854
  5. 282
  6. 127
  7. 100
  8. 387
  9. 157
  10. 513
  11. 984
  12. 813
  13. 1345
  14. 146
  15. 564
  16. 349
  17. 170
  18. 957
  19. 1112
  20. 375
  21. 687
  22. 240
  23. 780
  24. 266
  25. 1143
  26. 187
  27. 1006
  28. 189
  29. 759
  30. 847
  31. 676
  32. 905
  33. 369
  34. 520
  35. 1132
  36. 136
  37. 600
  38. 778
  39. 642
  40. 101

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