En un principio me atore, pero quedó
package PrimerosPasos;
public class FactorialPractica {
public static void main(String[] args) {
// TODO Auto-generated method stub
int fac = 10;
int num = fac;
for(int j=fac-1; j>0; j--) {
num=(j)*num;
}
System.out.println(num);
}
}