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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 569 · 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. 1.453 + 421 =
  2. 2.614 + 689 =
  3. 3.140 + 656 =
  4. 4.196 + 301 =
  5. 5.935 − 446 =
  6. 6.668 + 376 =
  7. 7.675 + 371 =
  8. 8.496 + 658 =
  9. 9.564 − 356 =
  10. 10.926 − 317 =
  11. 11.784 − 405 =
  12. 12.770 + 371 =
  13. 13.637 − 152 =
  14. 14.646 + 637 =
  15. 15.988 − 751 =
  16. 16.684 − 292 =
  17. 17.890 − 533 =
  18. 18.232 + 303 =
  19. 19.521 + 657 =
  20. 20.473 − 131 =
  21. 21.729 + 538 =
  22. 22.565 + 164 =
  23. 23.133 + 592 =
  24. 24.349 + 621 =
  25. 25.693 + 188 =
  26. 26.880 − 308 =
  27. 27.687 + 643 =
  28. 28.873 − 704 =
  29. 29.577 + 298 =
  30. 30.218 + 116 =
  31. 31.452 − 141 =
  32. 32.553 − 125 =
  33. 33.407 + 493 =
  34. 34.872 − 248 =
  35. 35.650 + 586 =
  36. 36.182 + 377 =
  37. 37.445 + 473 =
  38. 38.329 + 527 =
  39. 39.488 − 226 =
  40. 40.440 + 381 =

Answer key

  1. 874
  2. 1303
  3. 796
  4. 497
  5. 489
  6. 1044
  7. 1046
  8. 1154
  9. 208
  10. 609
  11. 379
  12. 1141
  13. 485
  14. 1283
  15. 237
  16. 392
  17. 357
  18. 535
  19. 1178
  20. 342
  21. 1267
  22. 729
  23. 725
  24. 970
  25. 881
  26. 572
  27. 1330
  28. 169
  29. 875
  30. 334
  31. 311
  32. 428
  33. 900
  34. 624
  35. 1236
  36. 559
  37. 918
  38. 856
  39. 262
  40. 821

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