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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 704 · 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. 1.971 − 775 =
  2. 2.756 − 491 =
  3. 3.236 + 364 =
  4. 4.549 − 389 =
  5. 5.219 + 135 =
  6. 6.504 − 396 =
  7. 7.769 + 371 =
  8. 8.181 + 271 =
  9. 9.246 + 169 =
  10. 10.938 − 708 =
  11. 11.844 − 471 =
  12. 12.741 + 385 =
  13. 13.169 + 279 =
  14. 14.739 + 478 =
  15. 15.250 + 671 =
  16. 16.508 + 544 =
  17. 17.790 − 198 =
  18. 18.612 − 137 =
  19. 19.590 − 225 =
  20. 20.149 + 405 =
  21. 21.788 − 363 =
  22. 22.662 − 237 =
  23. 23.822 − 467 =
  24. 24.234 + 531 =
  25. 25.750 − 199 =
  26. 26.686 + 119 =
  27. 27.697 + 324 =
  28. 28.279 + 471 =
  29. 29.891 − 181 =
  30. 30.476 + 271 =
  31. 31.249 + 166 =
  32. 32.922 − 658 =
  33. 33.241 + 409 =
  34. 34.377 + 134 =
  35. 35.721 + 336 =
  36. 36.568 + 631 =
  37. 37.526 − 138 =
  38. 38.505 − 275 =
  39. 39.630 − 168 =
  40. 40.721 − 183 =

Answer key

  1. 196
  2. 265
  3. 600
  4. 160
  5. 354
  6. 108
  7. 1140
  8. 452
  9. 415
  10. 230
  11. 373
  12. 1126
  13. 448
  14. 1217
  15. 921
  16. 1052
  17. 592
  18. 475
  19. 365
  20. 554
  21. 425
  22. 425
  23. 355
  24. 765
  25. 551
  26. 805
  27. 1021
  28. 750
  29. 710
  30. 747
  31. 415
  32. 264
  33. 650
  34. 511
  35. 1057
  36. 1199
  37. 388
  38. 230
  39. 462
  40. 538

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