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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 399 · 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. 1.546 − 394 =
  2. 2.608 + 174 =
  3. 3.662 − 342 =
  4. 4.502 − 307 =
  5. 5.642 − 421 =
  6. 6.267 + 357 =
  7. 7.520 − 284 =
  8. 8.246 + 279 =
  9. 9.680 − 478 =
  10. 10.731 + 223 =
  11. 11.656 + 169 =
  12. 12.574 − 116 =
  13. 13.168 + 124 =
  14. 14.904 − 739 =
  15. 15.912 − 147 =
  16. 16.570 − 281 =
  17. 17.574 − 239 =
  18. 18.530 − 328 =
  19. 19.976 − 579 =
  20. 20.773 − 443 =
  21. 21.354 + 461 =
  22. 22.522 + 121 =
  23. 23.694 − 552 =
  24. 24.959 − 571 =
  25. 25.955 − 214 =
  26. 26.938 − 679 =
  27. 27.569 − 281 =
  28. 28.691 + 179 =
  29. 29.663 − 144 =
  30. 30.502 + 421 =
  31. 31.730 − 266 =
  32. 32.919 − 778 =
  33. 33.192 + 593 =
  34. 34.452 − 129 =
  35. 35.636 − 188 =
  36. 36.373 + 576 =
  37. 37.420 − 181 =
  38. 38.562 + 251 =
  39. 39.281 + 378 =
  40. 40.171 + 127 =

Answer key

  1. 152
  2. 782
  3. 320
  4. 195
  5. 221
  6. 624
  7. 236
  8. 525
  9. 202
  10. 954
  11. 825
  12. 458
  13. 292
  14. 165
  15. 765
  16. 289
  17. 335
  18. 202
  19. 397
  20. 330
  21. 815
  22. 643
  23. 142
  24. 388
  25. 741
  26. 259
  27. 288
  28. 870
  29. 519
  30. 923
  31. 464
  32. 141
  33. 785
  34. 323
  35. 448
  36. 949
  37. 239
  38. 813
  39. 659
  40. 298

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