Pi takes 33 digits to get all 10 digits.
3.14159265358979323846264338327950
However, e only takes 21 digits.
2.71828182845904523536
Suppose you pick random digits from 0 to 9 with probability 1/10 of each digit. What is the average number of digits required to get all 10 digits?

(In reply to re: Leading answer (spoiler) by Math Man)

The way I interpreted it, it didn't matter about leading zeros, as you are certain to have some digit first, and without leading zeros the first expected lenght involved is just 9/9 instead of 10/10, but from then on it's still 10/9, etc. as now, whether the first digit was a zero or a guaranteed non-zero, it's still the same.

Posted by Charlie on 2012-07-08 23:30:43