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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 227 · 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. 1.757 − 578 =
  2. 2.917 − 151 =
  3. 3.824 − 671 =
  4. 4.578 + 168 =
  5. 5.915 − 425 =
  6. 6.441 − 261 =
  7. 7.516 − 128 =
  8. 8.502 + 675 =
  9. 9.396 + 502 =
  10. 10.445 + 402 =
  11. 11.453 + 527 =
  12. 12.493 + 618 =
  13. 13.735 + 656 =
  14. 14.252 + 277 =
  15. 15.894 − 771 =
  16. 16.580 − 248 =
  17. 17.276 + 551 =
  18. 18.981 − 611 =
  19. 19.978 − 877 =
  20. 20.491 + 685 =
  21. 21.142 + 578 =
  22. 22.191 + 296 =
  23. 23.312 + 217 =
  24. 24.305 + 286 =
  25. 25.456 + 285 =
  26. 26.537 + 418 =
  27. 27.802 − 614 =
  28. 28.526 + 315 =
  29. 29.190 + 155 =
  30. 30.734 − 325 =
  31. 31.149 + 221 =
  32. 32.320 + 263 =
  33. 33.287 + 296 =
  34. 34.355 + 531 =
  35. 35.422 − 322 =
  36. 36.722 − 573 =
  37. 37.261 + 131 =
  38. 38.144 + 381 =
  39. 39.593 − 388 =
  40. 40.215 + 349 =

Answer key

  1. 179
  2. 766
  3. 153
  4. 746
  5. 490
  6. 180
  7. 388
  8. 1177
  9. 898
  10. 847
  11. 980
  12. 1111
  13. 1391
  14. 529
  15. 123
  16. 332
  17. 827
  18. 370
  19. 101
  20. 1176
  21. 720
  22. 487
  23. 529
  24. 591
  25. 741
  26. 955
  27. 188
  28. 841
  29. 345
  30. 409
  31. 370
  32. 583
  33. 583
  34. 886
  35. 100
  36. 149
  37. 392
  38. 525
  39. 205
  40. 564

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