Number.prototype.plural = function(forms, hideNumber) {
        return (hideNumber ? '' : this.valueOf() + ' ') + forms.split('|')[Number.pluralIndex(this.valueOf())];
    };

    Number.pluralIndex = function(n) {
        return (n%10 == 1 && n%100 != 11 ? 0 : n%10 >= 2 && n%10 <= 4 && (n%100 < 10 || n%100 >= 20) ? 1 : 2);
    };

var plurals = [];
for (var i = 0; i < 25; i++) {
    plurals.push(i.plural('час|часа|часов'));
}
alert(plurals.join('\n'));