Answer 1

http://code.sololearn.com/cWlQ6WzcAT1g

#include <iostream>
#include <math.h>
using namespace std;

bool isPrime(unsigned int n) {
int i;
if (n < 2) {
return false;
}
for (i = 2; i <= sqrt(n); i++) {
if (n % i == 0) {
return false;
}
}
return true;
}

int main() {
int n;
cout << "Enter a number to check if it is prime" << endl;
cin >> n;
if (isPrime(n)) {
cout << n << " is prime.";
} else {
cout << n << " is not prime.";
}
return 0;
}