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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 464 · 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. 1.554 + 122 =
  2. 2.628 − 374 =
  3. 3.498 − 315 =
  4. 4.344 + 184 =
  5. 5.548 − 323 =
  6. 6.657 − 484 =
  7. 7.532 + 544 =
  8. 8.969 − 387 =
  9. 9.225 + 224 =
  10. 10.739 − 131 =
  11. 11.280 + 597 =
  12. 12.290 + 149 =
  13. 13.832 − 155 =
  14. 14.463 − 341 =
  15. 15.794 − 404 =
  16. 16.764 − 609 =
  17. 17.786 − 129 =
  18. 18.886 − 513 =
  19. 19.722 + 349 =
  20. 20.554 + 259 =
  21. 21.584 − 372 =
  22. 22.746 + 406 =
  23. 23.501 − 312 =
  24. 24.553 − 402 =
  25. 25.588 + 113 =
  26. 26.408 + 131 =
  27. 27.844 − 305 =
  28. 28.461 + 389 =
  29. 29.601 + 275 =
  30. 30.769 − 206 =
  31. 31.558 − 448 =
  32. 32.221 + 542 =
  33. 33.287 + 391 =
  34. 34.757 + 332 =
  35. 35.260 + 248 =
  36. 36.645 − 435 =
  37. 37.688 − 227 =
  38. 38.182 + 372 =
  39. 39.591 + 373 =
  40. 40.664 − 436 =

Answer key

  1. 676
  2. 254
  3. 183
  4. 528
  5. 225
  6. 173
  7. 1076
  8. 582
  9. 449
  10. 608
  11. 877
  12. 439
  13. 677
  14. 122
  15. 390
  16. 155
  17. 657
  18. 373
  19. 1071
  20. 813
  21. 212
  22. 1152
  23. 189
  24. 151
  25. 701
  26. 539
  27. 539
  28. 850
  29. 876
  30. 563
  31. 110
  32. 763
  33. 678
  34. 1089
  35. 508
  36. 210
  37. 461
  38. 554
  39. 964
  40. 228

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