screen/application/common/model/Admin.php

<?php

namespace app\common\model;

use think\Model;

/**
 */
class Admin extends Model
{
    /**
     * @param $amount
     * @return int|string
     */
    public static function getCmn($amount){
        $per=config('site.manager_commission_per')?:0;
        if($per<=0){
            return 0;
        }
        return bcmul($amount,$per/100);
    }
}