Answer:
Following are the code to the given question:
public class Main//defining a class Main
{
static int permut(int n, int r)//defining a method permut that holds two variable
{
return fact(n)/fact(n-r);//use return keyword to return calcuate value
}
static int fact(int n)//defining a fact method as recursive to calculate factorials
{
return n==0?1:n*fact(n-1);//calling the method recursively
}
public static void main(String[] abs)//main function
{
//int n=7,r=4;//defining integer variable
System.out.println(permut(7,4));//use print method to call permut method and print its values
}
}
Output:
840
Explanation:
Following is the explanation for the above code.