I'm sorry to spoil your party, but your script works for me. Like I already said in the Chatterbox, it probably is just waiting for you to enter data. Even if you don't see any prompts, try entering numbers followed by return at the console, and see if it responds to it.

If it does, and I bet it will, it would be a good idea to set

$| = 1;
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near the top of your script.

Furthermore, your gives a few warnings, caused by

undef $x;
for(@exes){
    $x=$x+$_;
}
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which can be fixed by eiter setting $x to 0 instead, or by doing

undef $x;
for(@exes){
    $x += $_;
}
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which does the same thing, but is shorter, and doesn't warn if $x is undef.

Worse, there's a nasty error, that makes your script output a wrong result: the power operator in Perl is **, not ^, which does XOR. See perlop. So:

for(@exes){
    $tot += ($_-$ave)**2;
}
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