I was working on this basic problem:

Factorials - Problem 1, C++ programming challenge, Java programming challenge



Code:
public class Factorials
{
    // n!
    public static long factorial( int n )
    {
        if( n <= 1 )     
            return 1;
        else
            return n * factorial(n-1);
    }


    public static void main(String [ ] args)
    {
        double temp = 0.0;
        double ans = 0.0;
        for( int i = 1; i <= 15; i++ ){
        temp = factorial( i );
        ans = (ans + temp);
            
    }
    System.out.println( ans );
}
}
I have the right answer but in the wrong format.

1.401602636313E12

How would i convert it to a decimal form?