Random Numbers and Cookies

I set a random number

$randomc = rand(1, 10000);

I set a cookie

setcookie("tpf",$randomc);

I echo back out the number and the cookie

Echo ("random number c: $randomc<br>");
echo $_COOKIE["tpf"];

 
What I get

The random number and cookie are different.
If I refresh the screen, I get a new random number (as expected) but the cookie becomes the last random number set.

I’ve looked at documentation for rand and mt_rand----I’m scratching my head.
I'm sure it's something basic...

Suggestions?