<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<!DOCTYPE html>
<html>
<body>
<input type="text" id="one" placeholder="Type">
<input type="text" id="two" placeholder="Type">
<input type="text" id="three" placeholder="Type">
<button onclick="chk()">Sum</button>
<p id="showof"></p>
<script>
function chk(){
cnd=document.getElementById('one').value
cnd1=document.getElementById('two').value
cnd2=document.getElementById('three').value
lav();
}
function lav(){
if(cnd2=='+'){
document.getElementById('showof').innerHTML=Number(cnd)+Number(cnd1)
}
else if(cnd2=='-'){
document.getElementById('showof').innerHTML=Number(cnd)-Number(cnd1)
}
else if (cnd2=='%'){
document.getElementById('showof').innerHTML=Number(cnd)/Number(cnd1)
}
else{
