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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 809 · 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. 1.263 + 189 =
  2. 2.159 + 372 =
  3. 3.499 − 378 =
  4. 4.516 + 427 =
  5. 5.789 + 603 =
  6. 6.373 + 338 =
  7. 7.888 − 253 =
  8. 8.759 − 581 =
  9. 9.748 + 261 =
  10. 10.662 − 281 =
  11. 11.344 + 217 =
  12. 12.494 − 135 =
  13. 13.703 − 209 =
  14. 14.478 − 359 =
  15. 15.529 − 116 =
  16. 16.651 + 545 =
  17. 17.577 + 131 =
  18. 18.637 + 147 =
  19. 19.670 − 174 =
  20. 20.565 − 178 =
  21. 21.736 + 171 =
  22. 22.430 − 251 =
  23. 23.639 + 158 =
  24. 24.831 − 567 =
  25. 25.542 + 508 =
  26. 26.714 + 139 =
  27. 27.623 − 522 =
  28. 28.816 − 194 =
  29. 29.820 − 299 =
  30. 30.651 + 356 =
  31. 31.297 + 222 =
  32. 32.645 + 389 =
  33. 33.586 − 213 =
  34. 34.708 + 268 =
  35. 35.626 − 338 =
  36. 36.216 + 458 =
  37. 37.915 − 784 =
  38. 38.172 + 263 =
  39. 39.416 − 169 =
  40. 40.877 − 181 =

Answer key

  1. 452
  2. 531
  3. 121
  4. 943
  5. 1392
  6. 711
  7. 635
  8. 178
  9. 1009
  10. 381
  11. 561
  12. 359
  13. 494
  14. 119
  15. 413
  16. 1196
  17. 708
  18. 784
  19. 496
  20. 387
  21. 907
  22. 179
  23. 797
  24. 264
  25. 1050
  26. 853
  27. 101
  28. 622
  29. 521
  30. 1007
  31. 519
  32. 1034
  33. 373
  34. 976
  35. 288
  36. 674
  37. 131
  38. 435
  39. 247
  40. 696

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