#!/usr/bin/perl -w 
use strict;

my @data=();
my $file='c:\text.txt';
my $count=0;
open FILE,"< $file" or die "$file: $!";

while (my $line =<FILE> ){
      chomp $line;
      push @data,[split /\t/,$line];
      $count++;
      next if $count < 99; 
      while ($#data >= 0 ) {
          printf "%s\n",join(",",shift @data);
      } 
      $count = 0;
}
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So.. how much more of your homework do you need me to do?