Changing items in $_POST

I have items from a form that will be in $_POST that I want to send on. I'll be using this: $arr = array(); foreach($_POST as $key => $value) { $arr[] = $key.'='.urlencode($value); } $URL = "https://example.com/script.asp?".implode('&',$arr); header("Location: $URL\n"); However, there are a few variables I need changed. For example, the people I'm sending it to need $rate_1m which is a mortgage rate but in $_POST there is $rate_1m1 (the whole number) and $rate_1m2 (the two numbers after the decimal). How do I get those two together and then discard the two numbers and only send $rate_1m? If that makes any sense. Thanks. Jeff