use strict;
use warnings;
my %h = (
  HEX => sub { return sprintf ("0x%x ", shift) },
  BIN => sub { return sprintf ("%b", shift) },
  DEC => sub { return sprintf ("%d", shift) },
);

my $value = 5;

for my $fmt (sort keys %h){
  print "$value in $fmt is: ", $h{$fmt}->($value) , "\n";
}