Depending on the file format, perhaps something like this? 
#!/usr/bin/perl

use strict;
use warnings;

my %prns;

for (<DATA>)
{
    my ( $num, $prn ) = split /\s/;
    $prns{$num} = $prn;
}

my @ord = sort { $b <=> $a } keys %prns;

print "Highest numbered printer is $prns{shift @ord}\n";

__DATA__
1 prt1
2 prt2
99 prt99
10 prt10
100 prt100
7 prt7

[download]
update
use strict;
use warnings;

my %prns;

for (<DATA>)
{
    my ( $printer, $num, $cmd ) = split /:/;
    $prns{$num} = $printer;
}

my @ord = sort { $b <=> $a } keys %prns;

print "Highest numbered printer is $prns{shift @ord}\n";

__DATA__
M08_amvpss09_MEDIP :275:lp -damvpss09
M07_amvpss09_MEDIP :279:lp -damvpss09
M09_amvpss09_MEDIP :278:lp -damvpss09
M01_amvpss09_MEDIP :2:lp -damvpss09
M04_amvpss09_MEDIP :1000:lp -damvpss09

[download]
Ted
--
"That which we persist in doing becomes easier, not that the task itself has become easier, but that our ability to perform it has improved."
  --Ralph Waldo Emerson

In reply to Re: Parsing a data file to find the highest value. by tcf03
in thread Parsing a data file to find the highest value. by misconfiguration

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