I don't believe you can do it with just one, but you can at least you should be able to work backwards: 
my $key = "31456"; # or whatever;
my $value = undef;
do { 
   $value = $hash{ $key };  # undef if not defined
   $key = substr( $key,  0, -1 );
} while ( !$value && $key );
# once value is set, this exits with the value
# once the key is exhausted, this exists

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In reply to Re: Fast lookup for prefixes in hash by Masem
in thread Fast lookup for prefixes in hash by Marcello

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