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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 849 · 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. 1.809 − 372 =
  2. 2.532 + 497 =
  3. 3.366 + 652 =
  4. 4.452 − 156 =
  5. 5.507 + 204 =
  6. 6.310 + 181 =
  7. 7.218 + 225 =
  8. 8.938 − 268 =
  9. 9.336 + 534 =
  10. 10.691 − 585 =
  11. 11.507 − 346 =
  12. 12.708 − 542 =
  13. 13.180 + 687 =
  14. 14.806 − 678 =
  15. 15.701 + 436 =
  16. 16.711 + 193 =
  17. 17.455 − 115 =
  18. 18.635 − 215 =
  19. 19.824 − 191 =
  20. 20.357 + 491 =
  21. 21.521 + 456 =
  22. 22.909 − 221 =
  23. 23.587 − 277 =
  24. 24.368 + 229 =
  25. 25.388 + 324 =
  26. 26.775 + 201 =
  27. 27.447 − 232 =
  28. 28.519 − 251 =
  29. 29.181 + 513 =
  30. 30.514 − 271 =
  31. 31.595 − 128 =
  32. 32.635 + 529 =
  33. 33.513 − 387 =
  34. 34.443 − 203 =
  35. 35.901 − 487 =
  36. 36.909 − 705 =
  37. 37.828 − 416 =
  38. 38.418 − 168 =
  39. 39.627 + 542 =
  40. 40.568 − 307 =

Answer key

  1. 437
  2. 1029
  3. 1018
  4. 296
  5. 711
  6. 491
  7. 443
  8. 670
  9. 870
  10. 106
  11. 161
  12. 166
  13. 867
  14. 128
  15. 1137
  16. 904
  17. 340
  18. 420
  19. 633
  20. 848
  21. 977
  22. 688
  23. 310
  24. 597
  25. 712
  26. 976
  27. 215
  28. 268
  29. 694
  30. 243
  31. 467
  32. 1164
  33. 126
  34. 240
  35. 414
  36. 204
  37. 412
  38. 250
  39. 1169
  40. 261

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