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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 846 · 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. 1.836 − 126 =
  2. 2.579 − 361 =
  3. 3.728 − 214 =
  4. 4.264 + 604 =
  5. 5.283 + 396 =
  6. 6.911 − 237 =
  7. 7.466 − 193 =
  8. 8.655 + 278 =
  9. 9.850 − 439 =
  10. 10.626 − 118 =
  11. 11.875 − 692 =
  12. 12.787 − 554 =
  13. 13.518 − 231 =
  14. 14.417 − 301 =
  15. 15.739 + 328 =
  16. 16.273 + 266 =
  17. 17.875 − 664 =
  18. 18.823 − 674 =
  19. 19.738 + 603 =
  20. 20.449 − 231 =
  21. 21.534 + 558 =
  22. 22.858 − 632 =
  23. 23.271 + 252 =
  24. 24.566 − 351 =
  25. 25.459 − 323 =
  26. 26.735 + 319 =
  27. 27.576 + 295 =
  28. 28.229 + 171 =
  29. 29.407 + 158 =
  30. 30.561 − 444 =
  31. 31.793 − 371 =
  32. 32.628 + 256 =
  33. 33.947 − 365 =
  34. 34.411 + 538 =
  35. 35.543 + 246 =
  36. 36.577 + 145 =
  37. 37.771 + 531 =
  38. 38.923 − 455 =
  39. 39.881 − 306 =
  40. 40.531 + 215 =

Answer key

  1. 710
  2. 218
  3. 514
  4. 868
  5. 679
  6. 674
  7. 273
  8. 933
  9. 411
  10. 508
  11. 183
  12. 233
  13. 287
  14. 116
  15. 1067
  16. 539
  17. 211
  18. 149
  19. 1341
  20. 218
  21. 1092
  22. 226
  23. 523
  24. 215
  25. 136
  26. 1054
  27. 871
  28. 400
  29. 565
  30. 117
  31. 422
  32. 884
  33. 582
  34. 949
  35. 789
  36. 722
  37. 1302
  38. 468
  39. 575
  40. 746

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