Hi Kate,
     I lost your question so I hope I am posting this answer to the
correct group.

     The problem with multiplying integers with large values is that
Pascal
insists on doing the math AS INTEGERS and then passing the answer.
Therefore
your must CAST the variables to a larger type:

      Answer:= Longint( Key ) * Longint ( Key );

Now it will do the math as Longint(s).

Please let me know if this worked for you.