Number.prototype.double = function () {

return this.valueOf()*2;

}

Number.prototype.square = function () {

return this.valueOf()*this.valueOf();

}

Number.prototype.fibonacci = function () {

function iterator(a, b, n) {

return n == 0n ? b : iterator((a+b), a, (n-1n))

}

function fibonacci(n) {

n = BigInt(n);

return iterator(1n, 0n, n);

}

return fibonacci(this.valueOf());

}

Number.prototype.factorial = function () {

factorial = (n) => {

n = BigInt(n);

return (n>1) ? n * factorial(n-1n) : n;

}

return factorial(this.valueOf());

}

let n = 100;

console.log(

"for number " + n +"\n",

"double is " + n.double() + "\n",

"square is " + n.square() + "\n",

"fibonacci is " + n.fibonacci() + "\n",

"factorial is " + n.factorial() + "\n"

);