Get your keys and check for matches.

my %hash = (
  a44 => 'aha!',
  b33 => 'boo!',
  c45 => 'close.',
  d44 => 'aha!',
  e44 => 'aha!',
  f46 => 'too far...',
);

my $r = 44;
foreach my $key (keys %hash){
        print $key."\n" if $key =~ /\w$r/;
}
__DATA__
e44
a44
d44
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