program expon;
    var
	x, answer: real;
	n: integer;

Procedure exp(var x: real; var n: integer; var ans: real);
    var
	subprod: real;
	nhalf: integer;
    begin
    if n = 0 then
	begin
        ans := 1.0;
	end
    else if (2 * (n div 2)) = n then {n is even}
	begin
	nhalf := n div 2;
	exp(x, nhalf, subprod);
	ans := subprod * subprod;
	end
    else {n must be odd}
	begin
	nhalf := n div 2;
	exp(x, nhalf, subprod);
	ans := x * subprod * subprod;
	end;
    end; {exp}

begin
writeln('x?');
readln(x);
writeln('n?');
readln(n);
exp(x, n, answer);
writeln(x:6:3, ' to the', n:4, ' power is ', answer:10:3);
readln;
end.

Sample output:

>x?
<2.0
>n?
<10
>  2.00 to the  10 power is   1024.000