This PHP snippet registers a [std_dev_calculator] shortcode that renders the same Standard Deviation Calculator inside any WordPress page or post. The code outputs the HTML structure and an inline JavaScript module that parses numbers, computes mean, variance and standard deviation (with option for population or sample), and displays a step-by-step breakdown. To use: place the PHP file into a plugin folder and activate it, or paste into your theme’s functions.php (backup first). Then add the shortcode [std_dev_calculator] to any post/page. This approach avoids external dependencies and works in most themes.