Your error occurs because $results is a string, and you're trying to use it as a hashref. For example:

  use strict;
  my $foo = "Hello World";
  exists $foo->{greeting}; # dies
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If you're trying to access your XML data as a hashref, then you probably want something like XML::Simple. However, there are a number of other errors and oddities with your code.

• </one/two/value> is not even close to well-formed XML. No XML parser will be able to parse the XML sample you provided above.
• $results{"$num"/"$value"} does not do what you think it does. The / is a numeric divide operator, so it treats "$num" and "$value" as numbers (both evaluate to 0). Dividing by zero will cause your code to die.