I'm guessing you have 9 digit numbers and you want to format them with hyphens. If so then perhaps unpack and join

#!perl
use strict;
use warnings;
while (<DATA>){
  my $str = join '-',unpack 'a3a2a4',$_;
  printf "%s\n",$str;
}

__DATA__
458430764
453453214
462634878
453990002
462755714
631036456
466917461
467172570
454691673
258611036
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