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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 728 · 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. 1.925 − 345 =
  2. 2.802 − 587 =
  3. 3.534 + 632 =
  4. 4.508 + 416 =
  5. 5.782 + 189 =
  6. 6.873 − 639 =
  7. 7.620 + 189 =
  8. 8.368 + 337 =
  9. 9.579 − 275 =
  10. 10.219 + 361 =
  11. 11.420 + 149 =
  12. 12.869 − 163 =
  13. 13.738 − 372 =
  14. 14.873 − 292 =
  15. 15.954 − 167 =
  16. 16.768 + 143 =
  17. 17.412 − 286 =
  18. 18.535 − 118 =
  19. 19.797 − 608 =
  20. 20.926 − 497 =
  21. 21.205 + 201 =
  22. 22.512 − 121 =
  23. 23.926 − 412 =
  24. 24.171 + 391 =
  25. 25.371 + 332 =
  26. 26.499 − 168 =
  27. 27.524 + 163 =
  28. 28.564 + 681 =
  29. 29.735 + 129 =
  30. 30.192 + 275 =
  31. 31.647 − 521 =
  32. 32.866 − 725 =
  33. 33.712 − 277 =
  34. 34.697 − 113 =
  35. 35.227 + 383 =
  36. 36.656 − 479 =
  37. 37.409 + 195 =
  38. 38.783 + 469 =
  39. 39.311 + 671 =
  40. 40.604 + 352 =

Answer key

  1. 580
  2. 215
  3. 1166
  4. 924
  5. 971
  6. 234
  7. 809
  8. 705
  9. 304
  10. 580
  11. 569
  12. 706
  13. 366
  14. 581
  15. 787
  16. 911
  17. 126
  18. 417
  19. 189
  20. 429
  21. 406
  22. 391
  23. 514
  24. 562
  25. 703
  26. 331
  27. 687
  28. 1245
  29. 864
  30. 467
  31. 126
  32. 141
  33. 435
  34. 584
  35. 610
  36. 177
  37. 604
  38. 1252
  39. 982
  40. 956

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