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Perfect number in java, program for perfect number in java

A perfect number is one where the sum of factors of a number (excluding the number itself) is equal to the number itself.

EXAMPLE-
We take 6. Factors of 6 are: 1,2,3
6 = 1 + 2 + 3
6 is a perfect number.

Now we take 28 .Factors of 28 are: 1,2,4,7,14
28 = 1 + 2 + 4 + 7 + 14
28 is a perfect number.

Perfect number in java language can be made by first applying a for loop starting from 1 to 1 less than that number and then with the help of if statement, checking if the number is divisible by that particular number which is currently stored in loop control variable. 

Then after the loop terminates we will check whether the sum of factors of the number is equal to the number itself or not. If the statement returns true then appropriate statement prints.
Here is the code for perfect number in two different formats firstly with the help of methods and secondly a very simple program using main method.
JAVA CODE ( with the help of methods)-
import java.util.*;
public class perfect
{
int num;
int sum;
perfect()
{
}
perfect(int nn)
{
num=nn;
}
int fact(int x)
{
int s=0;
for(int i=1;i<=x/2;i++)
{
 if(x%i==0)
{
s=s+i;
}
}
return s;
}
void isperfect()
 {
int n=num;
sum=0;
perfect obj=new perfect();
sum=sum+obj.fact(n);
if(sum==num)
System.out.println(num+" is a perfect number");
else
System.out.println(num+" is not a perfect number");
}
public static void main()
{
Scanner sc=new Scanner(System.in);
System.out.println("enter a number");
int e=sc.nextInt();
perfect obj=new perfect(e);
obj.isperfect();
}
}

Output-
enter a number
6
6 is a perfect number
enter a number
12
12 is not a perfect number


ALGORITHM-
 STEP 1: start
STEP 2: print"enter a number"
STEP 3: taking input of integer in e
STEP 4: sum = sum + STEP 8
STEP 5: repeat STEP 6 to STEP 7 until i<x/2
STEP 6: if x%i==0 then goto STEP 7
STEP 7: s=s+i
STEP 8: return s
STEP 9: if sum==num then goto STEP 10 else goto STEP 11
STEP 10: print num +"is a perfect number"
STEP 11: print num +"is not a perfect number" 
STEP 12: END

JAVA CODE ( WITHOUT USING METHOD)-
import java.util.*;
public class perfection
{
public static void main()
{
Scanner sc=new Scanner(System.in);
System.out.println("enter a number");
int num=sc.nextInt();
int sum=0;
for(int i=1;i<x;i++)
{
if(num%i==0)
sum+=i;
}
if(sum==num)
System.out.println(num+" is a perfect number);
else
System.out.println(num+" is not a perfect number");
}
}

Output-

enter a number
28
28 is a perfect number
enter a number
16
16 is not a perfect number

ALGORITHM-
 STEP 1: start
STEP 2: print "enter a number"
STEP 3: taking input in num
STEP 4: int i=1 ,repeat STEP 5 to STEP 6 until i    <num
STEP 5: if num%i==0 then goto STEP 6
STEP 6: sum=sum + i
STEP 7: if sum ==num then goto STEP 8 else goto STEP 9
STEP 8: print num+"is a perfect number"
STEP 9: print num+"is not a perfect number"
STEP 10:end

Related programs

 1-Prime number
If you have find this helpful please share .

 If you have any query related to this program then you can comment below.


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