Question

How to check whether a number is a perfect number in Java

Answer 1

// If the sum of all factors of a number is equal to the number, then the number is perfect
  
// 6
// factors = 1, 2, 3
// 1 + 2 + 3 = 6
 
public class MyClass {
    public static void main(String args[]) {
        int num = 6;
        int sumOfFactors = 0;
  
        for (int i = 1; i <= num / 2; i++)
            if (num % i == 0)
                sumOfFactors += i;
  
        if (sumOfFactors == num)
            System.out.println("Perfect Number");
        else
            System.out.println("Not a Perfect Number");
    }
}
 
 
 
/*
run:
 
Perfect Number
 
*/

 

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