← 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 515 · 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. 1.145 + 333 =
  2. 2.610 − 209 =
  3. 3.172 + 457 =
  4. 4.654 + 602 =
  5. 5.738 + 268 =
  6. 6.205 + 591 =
  7. 7.690 + 481 =
  8. 8.195 + 496 =
  9. 9.718 + 474 =
  10. 10.820 − 535 =
  11. 11.368 + 225 =
  12. 12.535 + 196 =
  13. 13.161 + 668 =
  14. 14.837 − 121 =
  15. 15.245 + 556 =
  16. 16.770 − 181 =
  17. 17.597 + 185 =
  18. 18.416 − 269 =
  19. 19.305 + 581 =
  20. 20.305 + 521 =
  21. 21.458 + 135 =
  22. 22.173 + 125 =
  23. 23.201 + 221 =
  24. 24.501 + 544 =
  25. 25.274 + 167 =
  26. 26.268 + 313 =
  27. 27.678 + 256 =
  28. 28.241 + 354 =
  29. 29.678 + 647 =
  30. 30.754 + 274 =
  31. 31.574 − 261 =
  32. 32.496 + 535 =
  33. 33.743 + 498 =
  34. 34.629 − 316 =
  35. 35.353 + 161 =
  36. 36.541 − 166 =
  37. 37.679 − 499 =
  38. 38.253 + 151 =
  39. 39.668 − 192 =
  40. 40.413 + 636 =

Answer key

  1. 478
  2. 401
  3. 629
  4. 1256
  5. 1006
  6. 796
  7. 1171
  8. 691
  9. 1192
  10. 285
  11. 593
  12. 731
  13. 829
  14. 716
  15. 801
  16. 589
  17. 782
  18. 147
  19. 886
  20. 826
  21. 593
  22. 298
  23. 422
  24. 1045
  25. 441
  26. 581
  27. 934
  28. 595
  29. 1325
  30. 1028
  31. 313
  32. 1031
  33. 1241
  34. 313
  35. 514
  36. 375
  37. 180
  38. 404
  39. 476
  40. 1049

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