<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>菜鸟教程(runoob.com)</title>
</head>
<body>
    
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = 123e5;
</script>
    
</body>
</html>

<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>菜鸟教程(runoob.com)</title> 
</head>
<body>
    
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = 'John Doe';
</script>
    
</body>
</html>

<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>菜鸟教程(runoob.com)</title> 
</head>
<body>
    
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = 5 * 10;
</script>
    
</body>
</html>

<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>菜鸟教程(runoob.com)</title> 
</head>
<body>

<p id="demo"></p>
<script>
var length;
length = 6;
document.getElementById("demo").innerHTML = length;
</script>

</body>
</html>

<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>菜鸟教程(runoob.com)</title> 
</head>
<body>

<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = (5 + 6) * 10;
</script>

</body>
</html>

<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>菜鸟教程(runoob.com)</title> 
</head>
<body>

<p id="demo"></p>
<script>
var x, y, z;
x = 5;
y = 6;
z = (x + y) * 10;
document.getElementById("demo").innerHTML = z;
</script>

</body>
</html>