If I see a number at random, what's the probability that the first digit is odd

This is a take-off of a currently posted Y!A question:

http://answers.yahoo.com/question/index;…

Benford's Law

As the number's aren't truly random, you can apply this Law.

Summing up the values for 1,3,5, 7 and 9, you get log_10 (256/63)
which is approximately 60.89%

The first digit of the number will be:

1,2,3,4,5,67,8 or 9 Total number of digits = 9

Odd digits are: 1,3,5,7 and 9. Total number of odd digits = 5

Hence, the probability thatthe first digit will be an odd digit is 5/9

It's 1/2. In this group of 10 numbers- take 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 - five begin odd and five begin even. From then on, it'll be ten odd, ten even...a hundred odd, a hundred even...it's 1/2.

The first digit of a number can't be 0, so you're choosing 1,3,5,7,9 as successful outcomes out of 1-9 (nine possibilities), so 5/9 is the probability.

wouldn't common sense say 50/50? that is my non scientific approach haha.

seriously though taking into account zero it makes the probability indefinite. The larger the sample the closer to 50% each number becomes