Either split the number into the various digits using a loop and divide / remainder, or convert it to a string and use a foreach loop on the characters:
while (myInt > 0)
{
myDigit = myInt % 10;
myInt /= 10;
... deal with myDigit ...
}
string myNumber = myInt.ToString();
int index = 0;
foreach (character c in myNumber)
{
... deal with each digit ...
}