JSFiddle - React, Tailwind, and code Playground

JavaScript

class Calculator {
	constructor(n) {
  	this.n = n;
  }
  sum(...nums) {
		nums.push(this.n);
    return nums.reduce((sum, k) => sum + k, 0);
	}
}

class SqrCalc extends Calculator {
  constructor(n) {
  	super(n);
  }
  sum(...nums) {
    let k = super.sum(...nums); 
  	return k * k;
  }
}

let myCalculator = new Calculator(100);
let myCalculator2 = new SqrCalc(100);

console.log(myCalculator.sum(2,2))
console.log(myCalculator2.sum(1,2,3));