C++ Add 10 to a number with function

#include <iostream>

using namespace std;
void addten(int); //function prototype
int main(){
    cout << "Program that takes a number and adds 10 using functions. \n\n";
    cout << "Enter a whole number: ";
    int number;
    cin >> number;
    cout << "\n";
    addten(number);
    return 0;
}

void addten(int n){
    n = n + 10;
    cout << "Number plus 10: " << n << "\n";

}