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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 836 · 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. 1.926 − 362 =
  2. 2.296 + 605 =
  3. 3.192 + 284 =
  4. 4.772 + 276 =
  5. 5.749 − 431 =
  6. 6.936 − 121 =
  7. 7.534 + 235 =
  8. 8.683 − 492 =
  9. 9.435 − 293 =
  10. 10.492 + 189 =
  11. 11.279 + 451 =
  12. 12.868 − 212 =
  13. 13.942 − 796 =
  14. 14.581 − 262 =
  15. 15.492 + 205 =
  16. 16.510 − 337 =
  17. 17.241 + 556 =
  18. 18.845 − 697 =
  19. 19.416 + 504 =
  20. 20.585 − 175 =
  21. 21.858 − 475 =
  22. 22.416 − 131 =
  23. 23.553 + 333 =
  24. 24.841 − 353 =
  25. 25.563 − 347 =
  26. 26.247 + 201 =
  27. 27.432 − 267 =
  28. 28.654 − 186 =
  29. 29.934 − 626 =
  30. 30.525 + 153 =
  31. 31.464 − 164 =
  32. 32.831 − 637 =
  33. 33.704 − 325 =
  34. 34.717 + 295 =
  35. 35.557 − 158 =
  36. 36.802 − 433 =
  37. 37.226 + 127 =
  38. 38.596 − 326 =
  39. 39.574 − 175 =
  40. 40.144 + 455 =

Answer key

  1. 564
  2. 901
  3. 476
  4. 1048
  5. 318
  6. 815
  7. 769
  8. 191
  9. 142
  10. 681
  11. 730
  12. 656
  13. 146
  14. 319
  15. 697
  16. 173
  17. 797
  18. 148
  19. 920
  20. 410
  21. 383
  22. 285
  23. 886
  24. 488
  25. 216
  26. 448
  27. 165
  28. 468
  29. 308
  30. 678
  31. 300
  32. 194
  33. 379
  34. 1012
  35. 399
  36. 369
  37. 353
  38. 270
  39. 399
  40. 599

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