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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 996 · 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. 1.507 − 175 =
  2. 2.777 + 551 =
  3. 3.698 − 596 =
  4. 4.722 − 261 =
  5. 5.586 − 215 =
  6. 6.639 − 445 =
  7. 7.407 + 494 =
  8. 8.335 + 426 =
  9. 9.577 + 597 =
  10. 10.437 + 208 =
  11. 11.540 − 201 =
  12. 12.538 + 306 =
  13. 13.835 − 581 =
  14. 14.461 + 579 =
  15. 15.533 + 251 =
  16. 16.584 + 418 =
  17. 17.936 − 821 =
  18. 18.194 + 257 =
  19. 19.942 − 208 =
  20. 20.329 + 223 =
  21. 21.308 + 357 =
  22. 22.710 + 413 =
  23. 23.782 + 289 =
  24. 24.249 + 431 =
  25. 25.670 + 422 =
  26. 26.921 − 171 =
  27. 27.720 − 468 =
  28. 28.828 − 176 =
  29. 29.819 − 169 =
  30. 30.419 + 427 =
  31. 31.370 + 143 =
  32. 32.577 − 136 =
  33. 33.446 − 129 =
  34. 34.453 + 469 =
  35. 35.426 − 131 =
  36. 36.696 − 581 =
  37. 37.834 − 596 =
  38. 38.219 + 215 =
  39. 39.598 − 134 =
  40. 40.771 + 277 =

Answer key

  1. 332
  2. 1328
  3. 102
  4. 461
  5. 371
  6. 194
  7. 901
  8. 761
  9. 1174
  10. 645
  11. 339
  12. 844
  13. 254
  14. 1040
  15. 784
  16. 1002
  17. 115
  18. 451
  19. 734
  20. 552
  21. 665
  22. 1123
  23. 1071
  24. 680
  25. 1092
  26. 750
  27. 252
  28. 652
  29. 650
  30. 846
  31. 513
  32. 441
  33. 317
  34. 922
  35. 295
  36. 115
  37. 238
  38. 434
  39. 464
  40. 1048

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