← 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 803 · 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. 1.689 + 619 =
  2. 2.532 − 252 =
  3. 3.786 + 154 =
  4. 4.862 − 272 =
  5. 5.413 + 162 =
  6. 6.676 − 194 =
  7. 7.137 + 493 =
  8. 8.752 + 445 =
  9. 9.635 + 237 =
  10. 10.688 + 141 =
  11. 11.415 − 275 =
  12. 12.966 − 645 =
  13. 13.966 − 681 =
  14. 14.981 − 849 =
  15. 15.150 + 596 =
  16. 16.701 − 187 =
  17. 17.412 − 118 =
  18. 18.353 + 455 =
  19. 19.495 + 229 =
  20. 20.136 + 183 =
  21. 21.469 + 153 =
  22. 22.515 − 178 =
  23. 23.925 − 491 =
  24. 24.668 + 298 =
  25. 25.401 + 401 =
  26. 26.325 + 129 =
  27. 27.827 − 195 =
  28. 28.142 + 117 =
  29. 29.664 + 403 =
  30. 30.388 + 328 =
  31. 31.578 − 305 =
  32. 32.593 + 589 =
  33. 33.430 − 256 =
  34. 34.482 + 117 =
  35. 35.772 − 667 =
  36. 36.935 − 736 =
  37. 37.727 + 479 =
  38. 38.654 + 551 =
  39. 39.465 − 295 =
  40. 40.570 + 152 =

Answer key

  1. 1308
  2. 280
  3. 940
  4. 590
  5. 575
  6. 482
  7. 630
  8. 1197
  9. 872
  10. 829
  11. 140
  12. 321
  13. 285
  14. 132
  15. 746
  16. 514
  17. 294
  18. 808
  19. 724
  20. 319
  21. 622
  22. 337
  23. 434
  24. 966
  25. 802
  26. 454
  27. 632
  28. 259
  29. 1067
  30. 716
  31. 273
  32. 1182
  33. 174
  34. 599
  35. 105
  36. 199
  37. 1206
  38. 1205
  39. 170
  40. 722

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