how do you Create a Web page that displays all numbers from 20 to 1 and indicates whether the number is prime in it displays?

To create a web page that displays numbers from 20 to 1 and indicates whether each number is prime or not, you will need a combination of HTML, CSS, and JavaScript. Here's a step-by-step guide on how to do it:

1. Set up the HTML structure:
Create an HTML file (e.g., index.html) and open it in a text editor. Add the following basic HTML structure:

```
<!DOCTYPE html>
<html>
<head>
<title>Prime Numbers</title>
<link rel="stylesheet" type="text/css" href="styles.css">
</head>
<body>
<h1>Prime Numbers from 20 to 1</h1>
<div id="primeNumbers"></div>
<script src="script.js"></script>
</body>
</html>
```

2. Style the page:
Create a CSS file (e.g., styles.css) in the same directory as the HTML file. Add the following CSS code to style the page:

```
body {
font-family: Arial, sans-serif;
text-align: center;
}

h1 {
margin-top: 20px;
}

#primeNumbers {
margin: 20px;
}
```

3. Add JavaScript functionality:
Create a JavaScript file (e.g., script.js) in the same directory as the HTML file. Add the following JavaScript code to generate the prime numbers and display them on the page:

```
function isPrime(num) {
if (num <= 1) {
return false;
}
for (let i = 2; i < num; i++) {
if (num % i === 0) {
return false;
}
}
return true;
}

function displayPrimeNumbers() {
const primeNumbersDiv = document.getElementById("primeNumbers");
let primeNumbersHTML = "";
for (let i = 20; i >= 1; i--) {
primeNumbersHTML += `<p>${i} - ${isPrime(i) ? "Prime" : "Not Prime"}</p>`;
}
primeNumbersDiv.innerHTML = primeNumbersHTML;
}

displayPrimeNumbers();
```

4. Test the web page:
Save all the files and open the index.html file in a web browser. It should display the numbers from 20 to 1 and indicate whether each number is prime or not.

Note: In the JavaScript code, the `isPrime()` function checks whether a number is prime by dividing it by numbers from 2 to the number itself minus one. If it has no divisors other than 1 and itself, it is considered prime.