← 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 345 · 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. 1.234 + 166 =
  2. 2.302 + 223 =
  3. 3.441 − 341 =
  4. 4.254 + 466 =
  5. 5.177 + 663 =
  6. 6.613 − 444 =
  7. 7.438 + 661 =
  8. 8.187 + 458 =
  9. 9.578 + 622 =
  10. 10.949 − 661 =
  11. 11.641 + 689 =
  12. 12.607 + 269 =
  13. 13.920 − 146 =
  14. 14.569 + 365 =
  15. 15.385 + 201 =
  16. 16.779 − 231 =
  17. 17.463 − 274 =
  18. 18.558 + 371 =
  19. 19.607 + 594 =
  20. 20.306 + 389 =
  21. 21.696 − 211 =
  22. 22.539 − 411 =
  23. 23.426 + 123 =
  24. 24.470 − 136 =
  25. 25.822 − 527 =
  26. 26.181 + 564 =
  27. 27.286 + 136 =
  28. 28.700 + 521 =
  29. 29.439 + 222 =
  30. 30.448 − 251 =
  31. 31.755 + 234 =
  32. 32.179 + 629 =
  33. 33.575 − 165 =
  34. 34.495 + 658 =
  35. 35.752 − 374 =
  36. 36.885 − 551 =
  37. 37.794 − 686 =
  38. 38.680 − 392 =
  39. 39.431 − 161 =
  40. 40.886 − 184 =

Answer key

  1. 400
  2. 525
  3. 100
  4. 720
  5. 840
  6. 169
  7. 1099
  8. 645
  9. 1200
  10. 288
  11. 1330
  12. 876
  13. 774
  14. 934
  15. 586
  16. 548
  17. 189
  18. 929
  19. 1201
  20. 695
  21. 485
  22. 128
  23. 549
  24. 334
  25. 295
  26. 745
  27. 422
  28. 1221
  29. 661
  30. 197
  31. 989
  32. 808
  33. 410
  34. 1153
  35. 378
  36. 334
  37. 108
  38. 288
  39. 270
  40. 702

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