index of same digits in any number

Question

HI!!!!!!!!!

How can I find the index of same digit which is at diffrent postion in any given number(number can be of any length)....
Like we have any number, suppose, 982625
How can we find the index of two 2s in this number.........
I have made a form in which there are two textboxes.In first ,i am entering number(which is 982625) and in second one I am entering the digit(i.e. 2)...
Can anyone provide me C# code for finding index values.............