Board Thread:Support Requests - Getting Technical/@comment-27023597-20151114042741/@comment-4018164-20151114121932

Summing multiple numbers is probably not something that you'd normally come across, but it shouldn't take too much to make. Since you want to write it yourself, here are a few methods that you could use to create your own feature: A quick google search should lead you to the methods for doing each one of these steps. You can always come back to the forum for help, of course.
 * Use JavaScript to first of all add the form to the page on which you want it to appear.
 * As an input, it's probably best to use the textarea element, which allows you to type a new number on each separate line.
 * When the "submit" button is clicked. You should:
 * Get the value of the textarea input, and split it to separate lines.
 * Have a 'sum' variable that is equals to 0.
 * Go through each line of the input. If it contains a valid number, add it to your sum.
 * Finally, insert the final sum into your output box.