function hesapla($x,$y){ 
    $result=0; 
    if($x>$y){ 
        $result=(($x-$y)/$y)*100; 
    }else{ 
        $result=(($y-$x)/$x)*100; 
    } 
    return sscanf($result, "%f")[0] /100; 
} echo hesapla(0.00008419,0.00008270);