You should know that => is only a "fat" comma, so my $tag1 = $words => $word; is the same as my $tag1 = $words, $word;, which is pointless. Note that => forces string-context on the left argument so you can write NAME => $value instead of "NAME", $value.

I think what you want is the following:

foreach my $word (sort keys  %tag) {
  my $fsize = $tag{$word};
  printf "<style=\"font-size:%dpx;\">%s\n", int($fsize), $word;
}
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PS: I would strongly recommend the use of:

use strict;
use warnings;
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