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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 89 · 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. 1.301 + 423 =
  2. 2.592 + 683 =
  3. 3.753 + 316 =
  4. 4.756 − 441 =
  5. 5.723 − 283 =
  6. 6.701 − 408 =
  7. 7.613 + 345 =
  8. 8.272 + 115 =
  9. 9.852 − 275 =
  10. 10.268 + 274 =
  11. 11.224 + 169 =
  12. 12.975 − 411 =
  13. 13.656 + 369 =
  14. 14.519 − 131 =
  15. 15.753 − 351 =
  16. 16.567 + 312 =
  17. 17.522 − 268 =
  18. 18.561 − 209 =
  19. 19.295 + 446 =
  20. 20.274 + 576 =
  21. 21.688 + 484 =
  22. 22.665 + 323 =
  23. 23.530 + 508 =
  24. 24.230 + 159 =
  25. 25.677 − 331 =
  26. 26.595 − 205 =
  27. 27.524 + 336 =
  28. 28.762 − 247 =
  29. 29.157 + 302 =
  30. 30.209 + 152 =
  31. 31.745 − 114 =
  32. 32.378 + 598 =
  33. 33.792 − 599 =
  34. 34.552 + 629 =
  35. 35.339 + 185 =
  36. 36.731 + 255 =
  37. 37.741 + 538 =
  38. 38.690 − 355 =
  39. 39.741 + 555 =
  40. 40.216 + 621 =

Answer key

  1. 724
  2. 1275
  3. 1069
  4. 315
  5. 440
  6. 293
  7. 958
  8. 387
  9. 577
  10. 542
  11. 393
  12. 564
  13. 1025
  14. 388
  15. 402
  16. 879
  17. 254
  18. 352
  19. 741
  20. 850
  21. 1172
  22. 988
  23. 1038
  24. 389
  25. 346
  26. 390
  27. 860
  28. 515
  29. 459
  30. 361
  31. 631
  32. 976
  33. 193
  34. 1181
  35. 524
  36. 986
  37. 1279
  38. 335
  39. 1296
  40. 837

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