Perfect Numbers In Java - ICSE Examples
14-05-2018    638 times

### Perfect No In Java - ICSE Examples

Write a program to print all the perfect nos between two limit enterd by the user with help of the following function

boolean IsPerfect(int num) - to return true if num is perfect otherwise print false.

A Number is said to be perfect if sum of all factors excluding itself should be equal to the number. Let N=6, Its factors are 1,2,3 and the sum of the factors (1+2+3)=6. So 6 is the perfect no. Examples of some Other perfect numbers are 28 and 496.

void showPerfectNumbers(int start,int end) - to print all the perfect nos between start and end limits by using functions IsPerfect().

Write a main function to execute the same.

import java.util.*;
public class PerfectNumbers
{
public boolean IsPerfect(int num)
{
int sum=0;
for(int k=1;k<= num/2;k++)
{
if(num%k==0)
{
sum=sum+k;
}
}
if(sum==num)
{
return true;
}
else
{
return false;
}
}
public void showPerfectNumbers(int start, int end)
{
System.out.println("Perfect Numbers are \n================");
for(int i=start;i<=end;i++)
{
if(IsPerfect(i))
{
System.out.println(i);
}
}
}
public static void main(String []args)
{
Scanner sc=new Scanner(System.in);
System.out.print("Enter Start Number:");
int s=sc.nextInt();
System.out.print("Enter end Number:");
int e=sc.nextInt();
PerfectNumbers pn=new PerfectNumbers();
pn.showPerfectNumbers(s,e);
}
}

#### Output

Enter Start Number:2
Enter end Number:900

Perfect Numbers are
================
6
28
496

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