Program to check the given number is perfect number or not
Perfect Number :-
A perfect number that is equal to the addition of all positive divisors, excluding the number itself.
Example:
Consider 6, the divisors of 6 are 1, 2 & 3. Thus, 1 + 2 + 3 = 6. Hence 6 is a Perfect Number.
Code
#include<bits/stdc++.h>
using namespace std;
int main(){
cout<<"Enter a Number"<<endl; //Requesting a number
int n; //To store the number
cin>>n; //Reading the number
int sum=0; //To store the sum of divisors
for(int i=1; i<n; i++){ //loop to go from 1 to given number
if(n%i==0){
sum=sum+i; //if the number is perfect divisor add to sum
}
}
//If the sum matches the original number then it's a perfect number
if(sum==n){
cout<<"It's a Perfect Number "<<endl;
}
//if sum is not equal to original number then it's not a perfect number
else{
cout<<"Not a Perfect Number"<<endl;
}
return 0;
}
Input
15
Output
Enter a Number
15
Not a Perfect Number
Program to print Perfect numbers from 1 to N.
#include<bits/stdc++.h>
using namespace std;
int main(){
cout<<"Enter a number"<<endl; //Requesting a Number
int n; //to store entered number
cin>>n; //Reading the number
for(int i=1; i<=n; i++){ //loop to go from 1 to N
int sum=0; //to store sum of divisors
for(int j=1; j<i; j++){ //loop to check divisors
if(i%j==0){
sum=sum+j; //if divides perfectly add to sum
}
}
if(sum==i){ //if sum matches original number print the number
cout<<i<<" ";
}
}
return 0;
}
Input
100
Output
Enter a number
100
6 28
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