number of trailing zeros in a factorial of a given number

number of trailing zeros in a factorial of a given number

by Kevin Mwangi

JavaScript

function zeros(n) {
    var result = 0;
    while (n = Math.floor(n / 5)) result += n;
    return result;
}


function trailing_zeros_factorial(n) {
    var result = 0;
    for (var i = 5; i <= n; i += 5) {
        var num = i;
        while (num % 5 === 0) {
            num /= 5;
            result++;
        }
    }
    return result;
}

/* function zeros(n) {
   if (n == 0) return 0;
   return n * (n-1)/(4*n);
} */

alert(zeros(1000));