How about ...

my $n = 3;

my $re = '(\d+)'.('\s+(\S+)' x $n);

my $qre = qr/$re/; # save it being compiled more than once

# no need to load it all in, we can just split it differently
# (assuming we can define a record separator)

$/ = "\n "; # might want to save old value or reset later 
            # or make a local block

while(<DATA>) {

  my @things = /$qre/;

  print "++ @things\n";
}

__DATA__
        654           -0.1192052729835885D-03 -0.1074533611698108D+02
0.2511576310952854D+05
        655           -0.1173814075917466D-03 -0.1074770905898570D+02
0.2511659074419869D+05
        656           -0.1169565901326905D-03 -0.1074824015295493D+02
0.2511670643648702D+05
        657           -0.1169057197333296D-03 -0.1074839256994435D+02
.2511658884706037D+05
        658           -0.1229838335208557D-03 -0.1074184682541694D+02
0.2511451830545289D+05
[download]

--
¤ Steve Marvell