Perfect number in java
A perfect number is a positive number (integer number) is the sum total of its factor
except for the number itself. For example 6, has factor 1, 2, 3 (except 6) and add
it all 1 + 2 + 3 = 6. Here summation of its divisors (excluding the number) is
equal to the original number.
In the
following code a number is taken by the user in n = sc.nextInt() and then with With the help of for loop, we do a summation of its divisor, less them the number. After
then with the help of if condition statement
if(s == n)
System.out.println("Perfect
Number");
else
System.out.println("Not a perfect
Number");
We check
the number is equal to the calculated summation in s. if both are equal then
the number is the perfect number.
import
java.util.*;
public
class PerfectNumber
{
public static void main(String args[])
{
int i, s=0, n;
Scanner sc=new Scanner(System.in);
System.out.println("Enter a number
:");
n=sc.nextInt();
for(i=1; i<n; i++)
{
if(n % i == 0)
s = s + i;
}
if(s == n)
System.out.println("Perfect
Number");
else
System.out.println("Not a perfect
Number");
}
}
Perfect number in java with the method.
The below
program is done with the help of a method
int
perfectNumber(int num)
{
sum = 0;
number = num;
for(i=1; i<number; i++)
{
if(number % i == 0)
sum =sum + i;
}
return sum;
}
In the
above piece of code we do the same calculation as above but within a block
called perfectNumber(int num) where the supplied number is sum up of its factor
(except the number itself) and return to
the value. Then in the main() method, it checked the original number and if it
is equal to the return value then that number is a perfect number.
import java.util.*;
public
class PerfectNumberMethod
{
private int i; // for iteraion
private int sum; // for summation of factor
private int number; // number to check
perfect number
int perfectNumber(int num)
{
sum = 0;
number = num;
for(i=1; i<number; i++)
{
if(number % i == 0)
sum =sum + i;
}
return sum;
} // end of perfect method
// main method started
public static void main(String args[])
{
int i, s, n;
PerfectNumberMethod ob = new
PerfectNumberMethod();
Scanner sc=new Scanner(System.in);
System.out.println ("Enter a
number :");
N = sc.nextInt();
s = ob.perfectNumber (n);
if(s == n)
System.out.println ("Perfect
Number");
else
System.out.println ("Not a
perfect Number");
}
}
Perfect number in java using recursion
import
java.util.*;
public
class PerfectNumberWithRecursion
{
int sum, number, i;
PerfectNumberWithRecursion()
{
sum = 0;
i = 1;
}
int perfectNumber(int num)
{
number = num;
if(i<=number/2)
{
if(number%i==0)
{
sum =sum + i;
}
i++;
perfectNumber(number);
}
return sum;
}
// main method started
public static void main(String arg[])
{
int n, s;
Scanner sc=new Scanner(System.in);
System.out.println("Enter a
number");
n=sc.nextInt();
PerfectNumberWithRecursion ob=new
PerfectNumberWithRecursion( );
s = ob.perfectNumber(n);
if(s == n)
System.out.println(n + " is a
perfect number");
else
System.out.println(n + " is
not a perfect number");
}
}
More Java program
