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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 13 · 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. 1.634 − 361 =
  2. 2.576 + 555 =
  3. 3.584 + 405 =
  4. 4.668 − 137 =
  5. 5.921 − 374 =
  6. 6.445 + 221 =
  7. 7.423 + 438 =
  8. 8.650 + 616 =
  9. 9.899 − 448 =
  10. 10.466 + 572 =
  11. 11.504 + 356 =
  12. 12.519 − 202 =
  13. 13.359 + 278 =
  14. 14.212 + 619 =
  15. 15.961 − 595 =
  16. 16.483 + 185 =
  17. 17.434 − 201 =
  18. 18.545 + 541 =
  19. 19.626 + 687 =
  20. 20.250 + 516 =
  21. 21.922 − 566 =
  22. 22.346 + 221 =
  23. 23.139 + 569 =
  24. 24.580 − 475 =
  25. 25.209 + 293 =
  26. 26.269 + 585 =
  27. 27.879 − 478 =
  28. 28.467 − 249 =
  29. 29.380 + 344 =
  30. 30.604 − 385 =
  31. 31.239 + 112 =
  32. 32.912 − 589 =
  33. 33.439 + 662 =
  34. 34.855 − 203 =
  35. 35.754 + 445 =
  36. 36.578 + 229 =
  37. 37.626 + 626 =
  38. 38.606 − 289 =
  39. 39.652 + 221 =
  40. 40.646 − 151 =

Answer key

  1. 273
  2. 1131
  3. 989
  4. 531
  5. 547
  6. 666
  7. 861
  8. 1266
  9. 451
  10. 1038
  11. 860
  12. 317
  13. 637
  14. 831
  15. 366
  16. 668
  17. 233
  18. 1086
  19. 1313
  20. 766
  21. 356
  22. 567
  23. 708
  24. 105
  25. 502
  26. 854
  27. 401
  28. 218
  29. 724
  30. 219
  31. 351
  32. 323
  33. 1101
  34. 652
  35. 1199
  36. 807
  37. 1252
  38. 317
  39. 873
  40. 495

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