Redirect/Rewrite

I am trying to redirect the page to a new location.
I am trying to go from http://localhost/page/image_archive.php?i=500
to http://localhost/gallery/500
The $query_string is causing an error. The query_string is i=500. How can I just get the number and not i=500 or whatever number.

location ~* ^/page/image_archive.php?$
{
return 302 http://127.0.0.1/gallery/$query_string;
}