Thank You so much for your quick responses!! After amending the program, it now seems to work..

#!/usr/bin/perl

use strict ;
use warnings ;

sub addition {
  my $sum ;
  my(@mynumbers) = @_ ;
  foreach (@mynumbers){
    $sum += $_ ;
  }
    return $sum
}

sub avg {
  my $aver ;
  my(@mynumbers) = @_ ;
  $aver = addition(@mynumbers)/($#mynumbers+1) ;
  print "$aver\n" ;
  return $aver ;
}

##
##THIS NOW WORKS!!! 
##

my (@numlist, $total, $average, $n, @greater) ;
chomp(@numlist = <STDIN>) ;
$total = addition(@numlist) ;
$average = avg(@numlist) ;
$n = 0 ;
foreach (@numlist) {
  if ($_ > $average) {
    $greater[$n] = $_ ;
#    push @greater,$_ ;
    $n++ ;
  }
}
if ( $n > 0 ) {
  print "Following numbers are greater than the average: " ;
  print "@greater. Array size is $#greater\n"     #IS THERE A WAY I CA
+N USE "$#greater+1" IN SOME WAY HERE?
  }
else {
  print "All your numbers are less than or equal to the average\n" ;
  }
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Now how do i use this above...
print "$#greater+1" ?
obviously this does not work as-...is
All said and done.. is this the best way to write the program in terms of coding standards?