Add to Formidable addition shortcode script to Multiply and Divide

[ramsaym]

I've got this code below that I'd like to add to in order to add multiplication and division to some short code. Here's the code:

 

add_shortcode('sum','my_entry_count');
function my_entry_count($atts){
    extract( shortcode_atts(array(
     'vals' => '0',
), $atts ) );
    $val_array = explode(',', $vals);
    $total = array_sum($val_array);
return $total;
}

 

I don't even know where to begin, as I'm a novice, but would assume somewhere around the array_sum I'd add a multiplication and division but don't know the code nor where to add it. Any help would be much appreciated! This is an add in script for Formidable Pro plugin for Wordpress if this helps at all. I'm trying to build in calculations into the shortcode, and apparently this is to add addition to