← 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 723 · 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. 1.687 + 451 =
  2. 2.553 − 379 =
  3. 3.977 − 571 =
  4. 4.988 − 333 =
  5. 5.700 + 675 =
  6. 6.281 + 434 =
  7. 7.426 + 195 =
  8. 8.308 + 541 =
  9. 9.412 + 351 =
  10. 10.528 + 417 =
  11. 11.157 + 338 =
  12. 12.960 − 157 =
  13. 13.365 + 185 =
  14. 14.684 − 411 =
  15. 15.543 − 174 =
  16. 16.734 + 461 =
  17. 17.412 + 561 =
  18. 18.572 − 144 =
  19. 19.659 + 653 =
  20. 20.561 + 681 =
  21. 21.564 + 553 =
  22. 22.137 + 592 =
  23. 23.428 − 113 =
  24. 24.230 + 298 =
  25. 25.404 + 261 =
  26. 26.583 + 171 =
  27. 27.780 + 221 =
  28. 28.362 + 644 =
  29. 29.638 − 491 =
  30. 30.687 + 173 =
  31. 31.210 + 576 =
  32. 32.220 + 435 =
  33. 33.428 + 401 =
  34. 34.569 + 259 =
  35. 35.762 + 221 =
  36. 36.437 + 154 =
  37. 37.629 + 256 =
  38. 38.134 + 474 =
  39. 39.378 + 371 =
  40. 40.180 + 661 =

Answer key

  1. 1138
  2. 174
  3. 406
  4. 655
  5. 1375
  6. 715
  7. 621
  8. 849
  9. 763
  10. 945
  11. 495
  12. 803
  13. 550
  14. 273
  15. 369
  16. 1195
  17. 973
  18. 428
  19. 1312
  20. 1242
  21. 1117
  22. 729
  23. 315
  24. 528
  25. 665
  26. 754
  27. 1001
  28. 1006
  29. 147
  30. 860
  31. 786
  32. 655
  33. 829
  34. 828
  35. 983
  36. 591
  37. 885
  38. 608
  39. 749
  40. 841

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