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C Program to Check whether a given number is Perfect or Not

 C Program to Check whether a given number is Perfect or Not.


In this exmaple we will learn to check a given number is a Perfect Number or not. 


LOGIC OF PERFECT SQUARE NUMBER:

  • At first we have declared variables i,num,sum=0(value is initialized to zero). 

  • Then we have inputted the number from the user and stored in num.

  • After that we have to to add a loop i=1 till num/2 and to increment the iteration by 1. You all must be thinking why we have to run the loop till num/2 because a number does not have any positive integer greater than the half of the number that is num/2.

  • Then we have to check whether the remainder of num%i is equal to zero or not. If it is equal then the value of i is a proper divisor of the number entered by the user and it is added to sum.

  • Now we have to check if the sum of the proper divisors of the number equal to the original number. If it is equal then the number entered by the user is a perfect number otherwise it is not a perfect number.


PROGRAM OF PERFECT NUMBER:

#include<stdio.h>
int main()
{
    int i,num,sum=0;
    printf("Enter any number to check perfect number:");
    scanf("%d",&num);
    for(i=1;i<=num/2;i++)
    {
        if(num%i==0)
        {
            sum+=i;
        }
    }
    if(sum==num)
    {
        printf("%d is PERFECT NUMBER\",num);
    }
    else
    {
        printf("%d is NOT A PERFECT NUMBER",num);
    }
    return 0;
}


OUTPUT:

C Program to Check whether a given number is Perfect or Not


PERFECT NUMBER:


Perfect number is a positive integer that is equal to the sum of its positive divisors, excluding the number itself. 


  • There are 51 known perfect numbers in total.

  • First five perfect numbers are 6,28,496,8128 and 33550336

  • There are only 2 perfect numbers between 1 to 100 and 3 perfect numbers between 1 to 1000.

  • Euclid was the first individual to categorize the perfect numbers.

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