Permutation Calculator

// Helper Function, generates factorials
function fact(num) {
    var rval = 1;
    for (var i = 2; i <= num; i++)
        rval = rval * i;
    return rval;
}

// Calculates number of possible permutations from set n, of length k
function permutations(n, k) {
    var p = fact(n);
    var v = fact(n-k);
    return p/v;
}

console.log(
    permutations(52, 52)
);