text: const Calculator = require('./calculator');
  const calc = new Calculator();
  
  console.log("1 + 2 is " + calc.add(1, 2));
  console.log("3 - 5 is " + calc.sub(3, 5));
  console.log("3 * 5 is " + calc.mul(3, 5));
  console.log("5 / 2 is " + calc.div(5, 2));
  console.log("log10 is " + calc.log(10));
  console.log("sin 360 is " + calc.sin(360));
  console.log("tan 180 is " + calc.tan(180));
  console.log("cos 120 is " + calc.cos(120));
  console.log("5! is " + calc.fact(-5));
  console.log("Sqrt 25 is " + calc.sqrt(25));
  console.log("4^4 is " + calc.pow(4, 4));
  
  console.log("SD of [1, 2, 3, 4, 5] is " + calc.sd([1, 2, 3, 4, 5]))
  
  console.log("mean between 3 and 87 is " + calc.mean(3,87));