HML 5 CALCULATE

<!DOCTYPE html>
<html lang="fr-CD">
<head>
<meta charset="utf-8" />
<meta http-equiv="Content-Type" content="text/html; utf-8" />
<meta name="description" content="HTML, CSS, JS calculator" />
<meta name="keywords" content="HTML, CSS, JS calculator" />
<meta name="author" content="Mr Deh H4ck3r" />
<title> HTML CALCULATOR </title>
<style type="text/css">
 input[type=button] {
  color: white;
  border-collaspe: collapse;
  padding: 20px 20px;
  border: 1px solid grey;
  background-color: rebeccapurple;
  font-size: 25px;
  border-radius: 10%;
  font-weight: 900;
  border-radius: 5px;
  width: 100%;
  outline: none;
  height: 75%;
  }
  table {
  background-color: black;
  border-radius: 15px;
  height: 550px;
  width: 350px;
  box-shadow: rgba(0, 0, 0, 0.19) 0px 10px 20px, rgba(0, 0, 0, 0.23) 0px 6px 6px;
  }
  input[type=button]:active {
   color: red;
   }
   input[type=button]:focus {
   color: red;
   }
  input[type=text] {
  padding: 20px 20px;
  text-align: left;
  font-weight: 900;
  border-radius: 10px;
  color: #651FFF;
  background-color: #DEDEF1;
  border: 4px solid green;
  box-shadow: 0px 0px 20px #cfcfcf;
  }
  input.btn {
  background-color: #FF1744;
  }
  input.btn1 {
  background-color: #F50057;
  }
</style>
</head>
<body>
<table border="0" class="calculate()">
<tr>
<td colspan="3"><input id="result" type="text" disabled></td>
<td><input type="button" value="del" onClick="clearScreen()" class="btn1" id="btn"></td>
</tr>
<tr>
<td><input type="button" value="1" onClick="display('1')"></td>
<td><input type="button" value="2" onClick="display('2')"></td>
<td><input type="button" value="3" onClick="display('3')"></td>
<td><input type="button" value="/" onClick="display('/')"></td>
</tr>
<tr>
<td><input type="button" value="4" onClick="display('4')"></td>
<th><input type="button" value="5" onClick="display('5')"></th>
<td><input type="button" value="6" onClick="display('6')"></td>
<td><input type="button" value="*" onClick="display('*')"></td>
</tr>
<tr>
<td><input type="button" value="7" onClick="display('7')"></td>
<td><input type="button" value="8" onClick="display('8')"></td>
<td><input type="button" value="9" onClick="display('9')"></td>
<td><input type="button" value="-" onClick="display('-')"></td>
</tr>
<tr>
<td><input type="button" value="." onClick="display('.')"></td>
<td><input type="button" value="0" onClick="display('0')"></td>
<td><input type="button" id="btn" class="btn" value="=" onClick="calculate()"></td>
<td><input type="button" value="+" onClick="display('+')"></td>
</tr>
</table>
<script type="text/javascript">
    // This function clear all the values
function clearScreen() {
    document.getElementById("result").value = "";
}

// This function display values
function display(value) {
    document.getElementById("result").value += value;
}

// This function evaluates the expression and returns result
function calculate() {
    var p = document.getElementById("result").value;
    var q = eval(p);
    document.getElementById("result").value = q;
}


</script>
</body>
</html>