Background

I'm working on a symmetric rounding class and I find that I'm stuck with regards to how to best find the number at position x that I will be rounding. I'm sure there is an efficient mathematical way to find the single digit and return it without having to resort to string parsing.

Problem

Suppose, I have the following (C#) psuedo-code:

var position = 3;
var value = 102.43587m;
// I want this no ? (that is 5)

protected static int FindNDigit(decimal value, int position)
{
    // This snippet is what I am searching for
}

Also, it is worth noting that if my value is a whole number, I will need to return a zero for the result of FindNDigit.

Does anyone have any hints on how I should approach this problem? Is this something that is blaringly obvious that I'm missing?