← 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 41 · 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. 1.685 + 441 =
  2. 2.503 + 381 =
  3. 3.783 − 118 =
  4. 4.515 − 332 =
  5. 5.635 + 115 =
  6. 6.730 + 129 =
  7. 7.693 + 251 =
  8. 8.297 + 671 =
  9. 9.714 + 228 =
  10. 10.877 − 458 =
  11. 11.361 + 125 =
  12. 12.624 − 372 =
  13. 13.619 − 372 =
  14. 14.813 − 364 =
  15. 15.272 + 211 =
  16. 16.436 + 294 =
  17. 17.530 − 393 =
  18. 18.498 − 348 =
  19. 19.278 + 277 =
  20. 20.841 − 401 =
  21. 21.378 + 126 =
  22. 22.163 + 308 =
  23. 23.659 − 384 =
  24. 24.957 − 499 =
  25. 25.466 + 333 =
  26. 26.505 + 255 =
  27. 27.783 − 141 =
  28. 28.205 + 524 =
  29. 29.458 + 452 =
  30. 30.762 − 187 =
  31. 31.876 − 661 =
  32. 32.328 + 668 =
  33. 33.277 + 121 =
  34. 34.263 + 651 =
  35. 35.605 − 358 =
  36. 36.626 + 311 =
  37. 37.488 − 384 =
  38. 38.470 − 293 =
  39. 39.463 − 341 =
  40. 40.558 + 289 =

Answer key

  1. 1126
  2. 884
  3. 665
  4. 183
  5. 750
  6. 859
  7. 944
  8. 968
  9. 942
  10. 419
  11. 486
  12. 252
  13. 247
  14. 449
  15. 483
  16. 730
  17. 137
  18. 150
  19. 555
  20. 440
  21. 504
  22. 471
  23. 275
  24. 458
  25. 799
  26. 760
  27. 642
  28. 729
  29. 910
  30. 575
  31. 215
  32. 996
  33. 398
  34. 914
  35. 247
  36. 937
  37. 104
  38. 177
  39. 122
  40. 847

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