tab@music4:~/Pianoforte/Development/Perlmonks/11113721 $ perl hashkeys.pl
At 11 there are 4 keys: $VAR1 = {
          '9' => 44,
          '1' => 5,
          '3' => 12,
          '7' => 19
        };
This should delete one of the keys, using this hash ..
$VAR1 = {
          '1' => 5,
          '9' => 22
        };
At 33 there are 3 keys: $VAR1 = {
          '9' => 22,
          '3' => 12,
          '7' => 19
        };
tab@music4:~/Pianoforte/Development/Perlmonks/11113721 $