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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 348 · 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. 1.884 − 455 =
  2. 2.213 + 672 =
  3. 3.404 + 263 =
  4. 4.182 + 523 =
  5. 5.359 + 531 =
  6. 6.462 − 306 =
  7. 7.158 + 331 =
  8. 8.908 − 375 =
  9. 9.200 + 633 =
  10. 10.250 + 524 =
  11. 11.295 + 588 =
  12. 12.366 + 601 =
  13. 13.441 − 316 =
  14. 14.742 + 113 =
  15. 15.216 + 517 =
  16. 16.542 + 339 =
  17. 17.550 − 149 =
  18. 18.890 − 516 =
  19. 19.641 + 682 =
  20. 20.601 − 371 =
  21. 21.554 − 177 =
  22. 22.941 − 153 =
  23. 23.540 − 301 =
  24. 24.511 + 334 =
  25. 25.916 − 809 =
  26. 26.549 − 122 =
  27. 27.764 − 486 =
  28. 28.664 + 443 =
  29. 29.984 − 693 =
  30. 30.424 + 307 =
  31. 31.934 − 131 =
  32. 32.737 + 212 =
  33. 33.893 − 733 =
  34. 34.416 + 265 =
  35. 35.928 − 367 =
  36. 36.461 − 307 =
  37. 37.919 − 171 =
  38. 38.750 + 167 =
  39. 39.692 + 361 =
  40. 40.513 − 291 =

Answer key

  1. 429
  2. 885
  3. 667
  4. 705
  5. 890
  6. 156
  7. 489
  8. 533
  9. 833
  10. 774
  11. 883
  12. 967
  13. 125
  14. 855
  15. 733
  16. 881
  17. 401
  18. 374
  19. 1323
  20. 230
  21. 377
  22. 788
  23. 239
  24. 845
  25. 107
  26. 427
  27. 278
  28. 1107
  29. 291
  30. 731
  31. 803
  32. 949
  33. 160
  34. 681
  35. 561
  36. 154
  37. 748
  38. 917
  39. 1053
  40. 222

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