[Alexandroppolus]

worldsering,

function number(num) {
    const inner = function(n) {
        const numberN = function(n1) {
            return inner(n * n1);
        }
        numberN.valueOf = function() { return n; };
        numberN.toString = function() { return String(n); };
        return numberN;
    }
    return inner(num);
}

const number5 = number(5);
const number10 = number5(2);
const number30 = number10(3);

const number15 = number5(3); // другая ветка умножения

alert([number5, number10, number30, number15, number10 + number15].join('\n'));