In this C program, we will check whether a number is perfect number or not. A number is a perfect number, if the sum of all the divisors of a number is equal to the number itself.
Algorithm to check a number is perfect number or not
- Take a number N as input from user.
- Find all divisors of a N between 1 to N/2.
- Add the values of all divisors to a variable sum.
- If sum is equal to N, then N is a perfect number otherwise not a perfect number.
C program to check a number is perfect number
#include<stdio.h>
int main () {
int num, i, divSum;
printf("Enter a number\n");
scanf("%d", &num);
for (divSum = 0, i = 1; i <= num/2; i++) {
if (num % i == 0) {
divSum += i;
}
}
/* Check if Divisor sum is equal to input number */
if (divSum == num)
printf("%d is a Perfect Number\n", num);
else
printf("%d is Not a Perfect Number\n", num);
return 0;
}
Output
Enter a number 10 10 is Not a Perfect Number
Enter a number 6 6 is a Perfect Number
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