Why do I see no computed results in my output file?

Question

This is a follow-up to How do I average column values from a tab-separated data file, ignoring a header row and the left column?. The task was: open and read a file; reach each

Answer 1

Specifying comments for each line to give you clear understanding

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

my $infile = "Lab1_table.txt";                         # input file path 
open INFILE, $infile or die "Can't open $infile: $!";  # input file opened
my $outfile = "Lab1_tableoutput.txt";                  # output file path
open OUTFILE, ">$outfile" or die "Cannot open $outfile: $!"; # output file opened

my $count = 0;              # count variable to check for header row in file 
my @header = ();            # variable to store headers/column names of file
my @average = ();           # variable to store average calculated for each column

while () {    
 chomp;
 my @columns = split /\s+/;   # \s stands for  [\ \t\r\n\f]
 $count++;    

 if ( $count == 1 ) {         
                    @header = @columns;      # executed only once for header 
      } 
 else {                                       # else column executed for remaining rows
        for( my $i = 1; $i < scalar @columns; $i++ ) {  # $i=1 means skip first column
              $average[$i] += $columns[$i];      # calcuate average for each row   
          }
      }
} 
for( my $i = 1; $i < scalar @average; $i++ ) {     

    print OUTFILE $average[$i]/($count-1), "\n";  # This will write to output file

    }     
close OUTFILE; 

Use print OUTFILE $average[$i]/($count-1), "\n"; to write to file.

Error Argument "" isn't numeric in addition (+) at line 25, line X could be if values in columns which you are adding,by any chance has string in it and not number.Check your input file.

Note: I am not getting above error.Script runs smooth with above data.However if I change one of number to string,I get this error.