<!DOCTYPE html>Here i used html5 doctype to create a simple calculator design.
CSS (CSS stands for Cascading Style Sheets) is used to give Styles and different Colours.
JavaScript is used to by taking the input from user and give out by using eval funtion,The eval() is a function property of the global object. The argument of the eval() function is a string. It will evaluate the source string as a script body, which means both statements and expressions are allowed. It returns the completion value of the code.
For Eg :
let x = 10;
let y = 20;
let text = "x * y";
let result = eval(text);