Perfect Number In Java Program

Perfect Number In Java Program

• What is Perfect Number?
• Find Single Perfect Number In Java Program
• Find Perfect  numbers from 1 to 100 and 1 to n

What is Perfect Number?

Perfect numbers are positive integers  such that

where  is the restricted divisor function (i.e., the sum of proper divisors of ), or equivalently

where  is the divisor function (i.e., the sum of divisors of  including  itself). For example, the first few perfect numbers are 6, 28, 496, 8128, ... 6 = 1+2+3, 28 = 1+2+4+7+14, 496 = 1+2+4+8+16+31+62+124+248, etc.

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Find Single Perfect Number In Java Program

package hpkingdom.com;

public class PerfectNumber {

public static void main(String[] args) {
int num = 28;
int sum = 0;
for (int i=2; i<num; i++)
{
if (num%i==0)
{
sum =sum+i;
}
}
if (sum==num)

{
System.out.println(num+" : is a Perfect Number");
}
else
{
System.out.println(num+" : is a Not Perfect Number");
}
}
}

Output:

Find  Perfect  numbers from 1 to 100 and 1 to n

package hpkingdom.com;

public class PerfectNumber {

public static void main(String[] args) {

for (int num=1; num<29; num++){
int sum = 0;
for (int i=1; i<num; i++)
{
if (num%i==0)
{
sum =sum+i;
}
}
if (sum==num)
{
System.out.println(num+" : is a Perfect Number");
}
else
{
System.out.println(num+" : is a Not Perfect Number");
}
}
}
}