← 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 23 · 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. 1.300 + 433 =
  2. 2.430 − 262 =
  3. 3.899 − 481 =
  4. 4.302 + 448 =
  5. 5.349 + 272 =
  6. 6.341 + 169 =
  7. 7.143 + 594 =
  8. 8.743 + 176 =
  9. 9.280 + 204 =
  10. 10.826 − 166 =
  11. 11.553 + 578 =
  12. 12.468 − 127 =
  13. 13.690 − 166 =
  14. 14.706 + 527 =
  15. 15.505 + 251 =
  16. 16.748 + 638 =
  17. 17.584 + 201 =
  18. 18.786 − 636 =
  19. 19.239 + 579 =
  20. 20.798 − 617 =
  21. 21.290 + 259 =
  22. 22.420 − 223 =
  23. 23.577 + 151 =
  24. 24.747 − 327 =
  25. 25.760 + 203 =
  26. 26.736 − 229 =
  27. 27.823 − 115 =
  28. 28.659 + 157 =
  29. 29.358 + 379 =
  30. 30.524 − 168 =
  31. 31.354 + 476 =
  32. 32.449 − 136 =
  33. 33.595 − 419 =
  34. 34.830 − 687 =
  35. 35.927 − 404 =
  36. 36.621 − 447 =
  37. 37.645 + 128 =
  38. 38.973 − 621 =
  39. 39.297 + 462 =
  40. 40.819 − 711 =

Answer key

  1. 733
  2. 168
  3. 418
  4. 750
  5. 621
  6. 510
  7. 737
  8. 919
  9. 484
  10. 660
  11. 1131
  12. 341
  13. 524
  14. 1233
  15. 756
  16. 1386
  17. 785
  18. 150
  19. 818
  20. 181
  21. 549
  22. 197
  23. 728
  24. 420
  25. 963
  26. 507
  27. 708
  28. 816
  29. 737
  30. 356
  31. 830
  32. 313
  33. 176
  34. 143
  35. 523
  36. 174
  37. 773
  38. 352
  39. 759
  40. 108

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