← Add and subtract 3-digit numbers left to right lesson New set →

3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 621 · 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. 1.789 + 164 =
  2. 2.818 − 187 =
  3. 3.724 + 179 =
  4. 4.722 − 571 =
  5. 5.782 − 129 =
  6. 6.679 + 333 =
  7. 7.983 − 642 =
  8. 8.621 − 263 =
  9. 9.829 − 149 =
  10. 10.467 + 507 =
  11. 11.729 − 263 =
  12. 12.416 − 278 =
  13. 13.558 − 321 =
  14. 14.209 + 263 =
  15. 15.883 − 707 =
  16. 16.310 + 169 =
  17. 17.487 + 224 =
  18. 18.165 + 197 =
  19. 19.971 − 273 =
  20. 20.847 − 519 =
  21. 21.458 + 317 =
  22. 22.388 + 113 =
  23. 23.320 + 402 =
  24. 24.460 + 375 =
  25. 25.773 + 481 =
  26. 26.166 + 238 =
  27. 27.314 + 533 =
  28. 28.903 − 538 =
  29. 29.312 + 644 =
  30. 30.709 − 114 =
  31. 31.945 − 616 =
  32. 32.339 + 204 =
  33. 33.861 − 489 =
  34. 34.294 + 459 =
  35. 35.306 + 114 =
  36. 36.626 + 504 =
  37. 37.719 − 201 =
  38. 38.538 + 481 =
  39. 39.895 − 473 =
  40. 40.723 + 304 =

Answer key

  1. 953
  2. 631
  3. 903
  4. 151
  5. 653
  6. 1012
  7. 341
  8. 358
  9. 680
  10. 974
  11. 466
  12. 138
  13. 237
  14. 472
  15. 176
  16. 479
  17. 711
  18. 362
  19. 698
  20. 328
  21. 775
  22. 501
  23. 722
  24. 835
  25. 1254
  26. 404
  27. 847
  28. 365
  29. 956
  30. 595
  31. 329
  32. 543
  33. 372
  34. 753
  35. 420
  36. 1130
  37. 518
  38. 1019
  39. 422
  40. 1027

Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths