The following snippet is what you want to use here (assuming I understand what you are trying to accomplish):

my @month_3_tables;

for my $x (0 .. $how_many_items) {
  if ($item eq "March") {
    push @month_3_tables, "<tr>.....</tr>";
  }
}
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Note that my example uses a programmer-friendly version of the for{} loop. Also, I'm not sure if you're using an if() statement for every month, but if not, then using push() to add an item to an array is much more efficient than trying to name variables such as $month_3_tables0, $month_3_tables1, $month_3_table2, etc, etc.

($month_3_tables.$x) .= "..."

The above line that you have within your program is invalid perl, as has already been stated within another reply to your post. Perl just doesn't work that way for creating variables. Technically, you could use the following line to replace yours:

${$month_3_tables . $x} = "<tr>...</tr>";

But that is just not the best way to go about this. Use an array, since this is the exact reason they were created :)