More scalable (Less memory), but with a less pretty output than idg's solution (Also closer to the specification - base column is a parameter): 
use strict;
use warnings;

my $basecol=shift @ARGV or die "WHat base col?";
my %h;
$basecol--; # zero based inside program.
while (<DATA>){
  chomp;
  my @f= split ;
  next unless @f > 1; 
  my $k = $f[$basecol];
  $h{$k}{COUNT}++;
  for my $col(0..$#f){
    next if $col==$basecol;
    $f[$col]=0  unless $f[$col]=~/^\d+$/;
    $h{$k}{FIELD}[$col]+= $f[$col];
  }
}

for (sort keys %h){
  print "$_\t $h{$_}{COUNT}\t";
  for my $f(@{ $h{$_}{FIELD} }){
     defined $f or $f='';
     print "$f\t";
  }
  print "\n";
}
__DATA__
U1     ID1     100     280
U1     ID1     137     250
U2     ID2     150     375
U1     ID2     100     100
U3     ID1     100     600
U9     ID3     137     200

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             When in doubt, mumble; when in trouble, delegate; when in charge, ponder. -- James H. Boren

In reply to Re: Perl Sum & Count column based data by NetWallah
in thread Perl Sum & Count column based data by ler224

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