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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 425 · 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. 1.168 + 266 =
  2. 2.311 + 321 =
  3. 3.695 − 326 =
  4. 4.675 − 447 =
  5. 5.220 + 208 =
  6. 6.879 − 171 =
  7. 7.295 + 542 =
  8. 8.559 + 267 =
  9. 9.568 − 441 =
  10. 10.361 + 567 =
  11. 11.545 + 538 =
  12. 12.566 − 342 =
  13. 13.791 − 581 =
  14. 14.678 − 168 =
  15. 15.648 − 475 =
  16. 16.945 − 356 =
  17. 17.782 + 136 =
  18. 18.747 − 272 =
  19. 19.692 − 505 =
  20. 20.661 − 353 =
  21. 21.168 + 585 =
  22. 22.873 − 256 =
  23. 23.566 − 398 =
  24. 24.228 + 408 =
  25. 25.948 − 363 =
  26. 26.522 − 141 =
  27. 27.292 + 322 =
  28. 28.619 − 326 =
  29. 29.152 + 638 =
  30. 30.164 + 238 =
  31. 31.287 + 465 =
  32. 32.655 + 231 =
  33. 33.594 − 458 =
  34. 34.857 − 208 =
  35. 35.448 + 195 =
  36. 36.948 − 616 =
  37. 37.531 + 323 =
  38. 38.214 + 504 =
  39. 39.239 + 169 =
  40. 40.415 − 166 =

Answer key

  1. 434
  2. 632
  3. 369
  4. 228
  5. 428
  6. 708
  7. 837
  8. 826
  9. 127
  10. 928
  11. 1083
  12. 224
  13. 210
  14. 510
  15. 173
  16. 589
  17. 918
  18. 475
  19. 187
  20. 308
  21. 753
  22. 617
  23. 168
  24. 636
  25. 585
  26. 381
  27. 614
  28. 293
  29. 790
  30. 402
  31. 752
  32. 886
  33. 136
  34. 649
  35. 643
  36. 332
  37. 854
  38. 718
  39. 408
  40. 249

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