/**
 * @param {number} n
 * @return {number}
 */
var trailingZeroes = function(n) {
    let x = 5;
    let zeroes = 0;
    while((n/x) >= 1) {
        zeroes += Math.floor(n / x);
        x = x * 5;
    }

    return zeroes;
};

// GRE Math thingy

// Time: O(log(n))
// Space: O(1)