[рони]

Alexandroppolus,
абалдеть всё сходится

function sum(x, y) {
    var res = "0";
    for (var i = 0; i < y; i++) res = diff(res, "" + x);
    return res
}

function diff(max, min) {
    if (+max < +min) {
        var t = max;
        max = min;
        min = t
    }
    max = max.split("").reverse();
    min = min.split("").reverse();
    var len = Math.max(max.length, min.length),
        result = [];
    for (var i = 0, b = 0, c = 0; i <= len; i++) {
        b = (+max[i] || 0) + (+min[i] || 0) + c;
        result[i] = b > 9 ? (c = 1, b - 10) : (c = 0, b)
    }
    return result.reverse().join("").replace(/^0+/, "")
}

function getFactZeros(x) {
    var z = 0;
    while (x) {
        x = x / 5 | 0;
        z += x
    }
    return z
}
var a = "23!*24!!*25!*26!!*27!!";
var arr = a.split("*");
var val = "1";
for (var k = 0; k < arr.length; k++)
    if (arr[k].substring(arr[k].length - 2) == "!!")
        if (parseInt(arr[k]) % 2 == 0)
            for (var l = 2; l <= parseInt(arr[k]); l = l + 2) val = sum(val, "" + l);
        else
            for (var h = 1; h <= parseInt(arr[k]); h = h + 2) val = sum(val, "" + h);
        else
    for (var i = 2; i <= parseInt(arr[k]); i++) val = sum(val, "" + i);
var zeros = val;
var count = 0;
for (var j = zeros.length - 1; j >= 0; j--)
    if (zeros[j] == 0) count++;
    else if (zeros[j] != 0) break;
console.log(zeros);
console.log(count);
console.log(getFactZeros(23) + getFactZeros(12) + getFactZeros(25) + getFactZeros(27));