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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 440 · 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. 1.425 − 177 =
  2. 2.417 − 151 =
  3. 3.193 + 306 =
  4. 4.978 − 565 =
  5. 5.323 + 517 =
  6. 6.879 − 599 =
  7. 7.325 + 301 =
  8. 8.692 + 482 =
  9. 9.742 − 232 =
  10. 10.816 − 335 =
  11. 11.735 + 687 =
  12. 12.474 − 161 =
  13. 13.737 − 508 =
  14. 14.471 − 324 =
  15. 15.403 + 346 =
  16. 16.458 + 343 =
  17. 17.604 − 181 =
  18. 18.288 + 301 =
  19. 19.640 + 413 =
  20. 20.324 + 321 =
  21. 21.574 − 251 =
  22. 22.514 − 392 =
  23. 23.748 + 395 =
  24. 24.648 + 668 =
  25. 25.590 − 461 =
  26. 26.131 + 463 =
  27. 27.452 − 158 =
  28. 28.766 + 502 =
  29. 29.591 + 209 =
  30. 30.183 + 179 =
  31. 31.476 − 146 =
  32. 32.654 + 605 =
  33. 33.508 − 169 =
  34. 34.242 + 151 =
  35. 35.158 + 271 =
  36. 36.800 − 397 =
  37. 37.187 + 453 =
  38. 38.561 − 129 =
  39. 39.550 − 418 =
  40. 40.174 + 651 =

Answer key

  1. 248
  2. 266
  3. 499
  4. 413
  5. 840
  6. 280
  7. 626
  8. 1174
  9. 510
  10. 481
  11. 1422
  12. 313
  13. 229
  14. 147
  15. 749
  16. 801
  17. 423
  18. 589
  19. 1053
  20. 645
  21. 323
  22. 122
  23. 1143
  24. 1316
  25. 129
  26. 594
  27. 294
  28. 1268
  29. 800
  30. 362
  31. 330
  32. 1259
  33. 339
  34. 393
  35. 429
  36. 403
  37. 640
  38. 432
  39. 132
  40. 825

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