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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 60 · 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. 1.571 − 281 =
  2. 2.518 + 343 =
  3. 3.600 − 318 =
  4. 4.599 + 347 =
  5. 5.324 + 621 =
  6. 6.815 − 472 =
  7. 7.592 + 187 =
  8. 8.421 + 252 =
  9. 9.494 + 649 =
  10. 10.948 − 541 =
  11. 11.418 − 149 =
  12. 12.583 + 234 =
  13. 13.425 − 168 =
  14. 14.569 + 286 =
  15. 15.278 + 433 =
  16. 16.416 + 371 =
  17. 17.590 − 168 =
  18. 18.242 + 599 =
  19. 19.184 + 116 =
  20. 20.629 + 525 =
  21. 21.357 + 131 =
  22. 22.370 + 604 =
  23. 23.948 − 831 =
  24. 24.789 + 305 =
  25. 25.276 + 466 =
  26. 26.816 − 271 =
  27. 27.248 + 247 =
  28. 28.896 − 272 =
  29. 29.490 + 319 =
  30. 30.290 + 143 =
  31. 31.565 + 159 =
  32. 32.179 + 148 =
  33. 33.228 + 366 =
  34. 34.453 − 123 =
  35. 35.779 − 501 =
  36. 36.344 + 526 =
  37. 37.569 − 203 =
  38. 38.686 − 403 =
  39. 39.305 + 296 =
  40. 40.451 + 553 =

Answer key

  1. 290
  2. 861
  3. 282
  4. 946
  5. 945
  6. 343
  7. 779
  8. 673
  9. 1143
  10. 407
  11. 269
  12. 817
  13. 257
  14. 855
  15. 711
  16. 787
  17. 422
  18. 841
  19. 300
  20. 1154
  21. 488
  22. 974
  23. 117
  24. 1094
  25. 742
  26. 545
  27. 495
  28. 624
  29. 809
  30. 433
  31. 724
  32. 327
  33. 594
  34. 330
  35. 278
  36. 870
  37. 366
  38. 283
  39. 601
  40. 1004

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