Hi i am writing a program to compute the smallest number divisible by each of the numbers 1 to 20. This is what i have so far but it does not cout anything. it just gives me a blank page. Could anyone please help

```
#include<iostream.h>
#include<math.h>
bool div(ull y)
{
for(int x=1;x<=20;x++)
if(y%x!=0)
return false;
return true;
}
int main()
{
for(int x=1;;x++)
if(div(x)){
cout << x << endl;
system("pause");
}
}
```