← 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 29 · 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. 1.752 + 431 =
  2. 2.875 − 742 =
  3. 3.684 + 221 =
  4. 4.493 − 311 =
  5. 5.147 + 442 =
  6. 6.448 − 125 =
  7. 7.682 − 245 =
  8. 8.639 + 638 =
  9. 9.690 + 383 =
  10. 10.724 − 545 =
  11. 11.656 − 502 =
  12. 12.227 + 169 =
  13. 13.138 + 547 =
  14. 14.437 + 212 =
  15. 15.745 − 526 =
  16. 16.216 + 301 =
  17. 17.386 + 652 =
  18. 18.737 − 145 =
  19. 19.683 − 271 =
  20. 20.610 + 561 =
  21. 21.946 − 831 =
  22. 22.773 − 147 =
  23. 23.613 + 381 =
  24. 24.451 − 224 =
  25. 25.486 + 149 =
  26. 26.257 + 449 =
  27. 27.965 − 821 =
  28. 28.980 − 202 =
  29. 29.826 − 568 =
  30. 30.592 + 559 =
  31. 31.490 + 532 =
  32. 32.276 + 605 =
  33. 33.468 + 494 =
  34. 34.581 + 612 =
  35. 35.463 − 317 =
  36. 36.394 + 121 =
  37. 37.608 + 392 =
  38. 38.453 + 273 =
  39. 39.736 − 285 =
  40. 40.556 − 433 =

Answer key

  1. 1183
  2. 133
  3. 905
  4. 182
  5. 589
  6. 323
  7. 437
  8. 1277
  9. 1073
  10. 179
  11. 154
  12. 396
  13. 685
  14. 649
  15. 219
  16. 517
  17. 1038
  18. 592
  19. 412
  20. 1171
  21. 115
  22. 626
  23. 994
  24. 227
  25. 635
  26. 706
  27. 144
  28. 778
  29. 258
  30. 1151
  31. 1022
  32. 881
  33. 962
  34. 1193
  35. 146
  36. 515
  37. 1000
  38. 726
  39. 451
  40. 123

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