Find Factorial By Using Pthread

#include<iostream>
#include<pthread.h>
using namespace std;
int num;
void* factorial()
{
int fac=1;
for(int a=1;a<=num;a++) 
{
fac=fac*a;
cout<<"Factorial of Given Number is ="<<fac;
}
}
int main()
{
pthread_t t;
cout<<" Enter Number To Find Its Factorial: ";
cin>>num;
pthread_create (&t,NULL,factorial,(void*)&num);return 0;
}