# C program to check perfect number

### What is perfect number?

Perfect number is a positive number which sum of all positive divisors excluding that number is equal to that number. For example 6 is perfect number since divisor of 6 are 1, 2 and 3.
Sum of its divisor is 1 + 2+ 3 =6

Note: 6 is the smallest perfect number.

Next perfect number is 28 since 1+ 2 + 4 + 7 + 14 = 28

Some more perfect numbers: 496, 8128

#include
int main(){
int n,i=1,sum=0;
printf("Enter a number: ");
scanf("%d",&n);
while(i if(n%i==0)
sum=sum+i;
i++;
}
if(sum==n)
printf("%d is a perfect number",i);
else
printf("%d is not a perfect number",i);
return 0;
}

## C program to find perfect numbers with in a range

#include
int main(){
int n,i,sum;
int min,max;
printf("Enter the minimum range: ");
scanf("%d",&min);
printf("Enter the maximum range: ");
scanf("%d",&max);
printf("Perfect numbers in given range is: ");
for(n=min;n<=max;n++){
i=1;
sum = 0;
while(i if(n%i==0)
sum=sum+i;
i++;
}
if(sum==n)
printf("%d ",n);
}
return 0;
}

## C program to print perfect numbers from 1 to 100

#include
int main(){
int n,i,sum;
printf("Perfect numbers are: ");
for(n=1;n<=100;n++){
i=1;
sum = 0;
while(i if(n%i==0)
sum=sum+i;
i++;
}
if(sum==n)
printf("%d ",n);
}
return 0;
}

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