Multiple choice general knowledge math & puzzles

How many three-digit numbers can be generated from 1, 2, 3, 4, 5, 6, 7, 8, 9 such that the digits are1 in ascending order ?

  1. 80

  2. 81

  3. 83

  4. 84
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

To form a three-digit number with digits in ascending order from 1-9, we simply need to choose any 3 distinct digits - there's exactly one way to arrange them in ascending order. This is a combination problem: 9C3 = 9!/(3!×6!) = (9×8×7)/(3×2×1) = 84. The key insight is that choosing digits determines the arrangement uniquely.

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