Wordpress calc Plugin found on http://stackoverflow.com/questions/23207577/php-custom-calculator-script-wordpress-integration

calc.php

<?php
/*
Plugin Name: calc
Plugin URI: 
Description: Calculates loans/how much can be borrowed
Version: 1.0
Author: Mikey
Author URI: 
*/

// from http://stackoverflow.com/questions/23207577/php-custom-calculator-script-wordpress-integration
// Save as calc.php and drop into plugins folder
// Use Shortcode [bcalc] to show the calculator

//WordPress Hooks 
add_shortcode('bcalc', 'run_bc'); 

function run_bc() 
{ 
    if (isset($_POST['bc_person1'])) $bc_person1 = $_POST['bc_person1'];
    if (isset($_POST['bc_person2'])) $bc_person2 = $_POST['bc_person2'];
    $bc_multivar = 4;
    $bc_answer = ($bc_person1 + $bc_person2) * $bc_multivar;

?>
    <form method='post' action='<?php echo get_permalink(); ?>'>
        <table border='0' width='500px' cellpadding='3' cellspacing='1' class='table'>
            <tr class='calcheading'><td colspan='2'><strong>How much can you borrow?</strong></td></tr>
            <tr class='calcrow'><td>Person 1 income:</td>
            <td align='center'><input type='text' name='bc_person1' value='<?php echo $bc_person1 ?>'/></td></tr>
            <tr class='calcrow2'><td>Person 2 income</td><td align='center'><input type='text' name='bc_person2' value='<?php echo $bc_person2 ?>'/></td></tr>
            <tr class='submit'><td colspan='2'><input type='submit' value='Calculate'/></td></tr>
            <tr class='calcrow'>
            <td><i>You can borrow up to:</td>
            <td align='center'><input type='text' value='<?php echo round($bc_answer); ?>'></td></i>
            </tr>
        </table>
    </form>

<?php
}