Calculating a various number of facultys

Question

im trying to implement a way to calculate facultys with for loops for a university project. I wrote a for loop that increases in steps of two, while another for loop calculates each faculty for the first for loop.

Can anybody point out where i made a mistake?

package Cosinus;

public class MainCos {
     public static void main(String[] args) { 
         
         
         int fact=1;
        for(int number = 0; number <= 10; number += 2) {
              for(int i=1;i<=number;i++){
              fact=fact*i;
         }
         System.out.println("The Faculty of " + number + " is: " + fact);
        }
    }
}

Please check the [tour] and [ask] links and improve this question including telling more of the details of your actual requirements, your code and your problem. — Hovercraft Full Of Eels, Mar 20 '22 at 14:02

Justin · Answer 1 · 2022-03-20T14:13:54.293

1

I know it is hard for the first time, to figure factorial out, but basically, you need to multiply each number by the next integer so on. There are many ways to solve it, one way you can create a method either recursively or iteratively. I would prefer iterator here a for loop perhaps.

n! factorial You can also say it is n! or n factorial in general. now S = 5! 1 * 2 * 3 * 4 * 5 = 120 in decimal.

        long fact = 1;
        for (long count = 2; count <= 10; count++) {
            fact = fact * count;
            System.out.println("The Faculty of " + count + " is: " + fact);
        }

edited Mar 20 '22 at 14:13

answered Mar 20 '22 at 14:05

Justin

177
8

Where does the question mention "factorial"? – Hovercraft Full Of Eels Mar 20 '22 at 14:07
He wants to calculate faculty, it is the same as factirial n! – Justin Mar 20 '22 at 14:09
@HovercraftFullOfEels In my country fakulitet means factorial calculation, I asume it is the same in english (= – Justin Mar 20 '22 at 14:10

Idle_Mind · Answer 2 · 2022-03-20T15:59:27.893

If you're trying to compute the factorial of the even numbers, then just move int fact=1; to between the for loops so that it gets reset for each new number:

for(int number = 0; number <= 10; number += 2) {
  int fact=1;
  for(int i=1;i<=number;i++){
    fact=fact*i;
   }
   System.out.println("The Faculty of " + number + " is: " + fact);
}

Output:

The Faculty of 0 is: 1
The Faculty of 2 is: 2
The Faculty of 4 is: 24
The Faculty of 6 is: 720
The Faculty of 8 is: 40320
The Faculty of 10 is: 3628800

As others have pointed out, though, there is no need for nested loops here. Another approach would be to use just the outer loop, incrementing by one, and only display the factorial for even numbers. I've also added in the base condition of 0! = 1 :

int fact=0;
for(int number = 0; number <= 10; number++) {
  if (number == 0) {
    fact = 1; // by definition
  }
  else {
    fact = fact * number;  
  }
  if (number % 2 == 0) {
    System.out.println("The Faculty of " + number + " is: " + fact);
  }
}

Producing the same output:

The Faculty of 0 is: 1
The Faculty of 2 is: 2
The Faculty of 4 is: 24
The Faculty of 6 is: 720
The Faculty of 8 is: 40320
The Faculty of 10 is: 3628800

Good one, looks great, It is actually better than my solution (= — Justin, Mar 20 '22 at 16:04

Calculating a various number of facultys

2 Answers2