A params parameter may appear as the last parameter of a parameter list: it permits a variable number of arguments. Here is an example:

private static int iHowMany(int pTestValue, params int[] pValues)
{
    int tResult = 0;
    for (int tIndex = 0; tIndex<pValues.Length; tIndex++)
    {
        if (pValues[tIndex]==pTestValue)
        {
            tResult++;
        }
    }
    return tResult;
}
...
int tNumberFound = iHowMany(3, 1, 3, 3, 2);
// tNumberFound now has the value 2