${ 'radio_' . $ucount } = param( "radio_$ucount" );
${ "textarea$ucount" } = param( 'textarea' . $ucount );

##</code><code>##

print "something$ucount"; # prints 'something1'
print 'something$ucount'; # prints 'something$ucount'

##</code><code>##

$x = "something$ucountElse"; 
# probably tries to interpolate a variable called 
# $ucountElse, ambiguous
$x = "something" . $ucount . "Else"; # Unambiguous

##</code><code>##

$x = "something${ucount}Else";