Taking our anonymous brother's spec literally, here is a solution which produces the actual output he says is desired:

use strict;
use warnings;

while (my $line = <DATA>) {
    my ($key, @nums) = split /[\s-]+/, $line;
    $key =~ s/f$/d/;
    print "$key $_\n" for @nums;
}

__DATA__
abcd    723-724
abcde   552-554-553
abcdef  756

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In reply to Re: regex problem by hippo
in thread regex problem by Anonymous Monk

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