1). Make input type text feilds and buttons inside HTML
2). Make a function in Javascript by the name of getNumber() and assign it a parameter of num. Next I have called the function getNumber in every button using onclick event handler except the Clear button and the "=" sign button. In the argument of the function I have passed the respective values.
3). In the input text feild I created an id of result which I have called in a variable using document.getElementById(). Next I passed the variable with value attribute.
4). Next up I added the functionality to my Clear button. For that I created a function by the name of clearNumber() in app.js file and passed the function call in the Clear button using onclick event handler. Inside the function expression I pasted the same variable that I created in previous funciton and passed the variable with value which is equal to an empty string. This empty string will clear the text feild.
5). Now to display the result of the calculation I created another function by the name of getResult() in app.js file and passed the function call in the "=" button using onclick event handler. Inside the function expression I pasted the same variable that I created in previous funciton and passed the variable with value which was using a JS method "eval" meaning ecaluation and inside parenthesis passed the result.value, this method gives the result of math expression.