← 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 447 · 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. 1.309 + 552 =
  2. 2.542 + 677 =
  3. 3.657 + 322 =
  4. 4.910 − 324 =
  5. 5.754 − 341 =
  6. 6.194 + 539 =
  7. 7.599 + 521 =
  8. 8.950 − 801 =
  9. 9.808 − 272 =
  10. 10.663 + 559 =
  11. 11.738 + 392 =
  12. 12.610 − 162 =
  13. 13.246 + 433 =
  14. 14.779 + 306 =
  15. 15.789 − 551 =
  16. 16.606 + 673 =
  17. 17.181 + 499 =
  18. 18.798 − 447 =
  19. 19.559 + 663 =
  20. 20.296 + 651 =
  21. 21.881 − 252 =
  22. 22.521 + 451 =
  23. 23.702 − 441 =
  24. 24.425 − 259 =
  25. 25.555 + 389 =
  26. 26.529 − 254 =
  27. 27.265 + 241 =
  28. 28.134 + 164 =
  29. 29.593 + 192 =
  30. 30.757 − 452 =
  31. 31.751 + 119 =
  32. 32.805 − 347 =
  33. 33.451 + 435 =
  34. 34.835 − 438 =
  35. 35.572 − 259 =
  36. 36.240 + 155 =
  37. 37.164 + 361 =
  38. 38.487 + 517 =
  39. 39.185 + 163 =
  40. 40.499 + 498 =

Answer key

  1. 861
  2. 1219
  3. 979
  4. 586
  5. 413
  6. 733
  7. 1120
  8. 149
  9. 536
  10. 1222
  11. 1130
  12. 448
  13. 679
  14. 1085
  15. 238
  16. 1279
  17. 680
  18. 351
  19. 1222
  20. 947
  21. 629
  22. 972
  23. 261
  24. 166
  25. 944
  26. 275
  27. 506
  28. 298
  29. 785
  30. 305
  31. 870
  32. 458
  33. 886
  34. 397
  35. 313
  36. 395
  37. 525
  38. 1004
  39. 348
  40. 997

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