how do i get a pointer to "point" to a variable in another function?

this is what i have so far.

Code:

# include <conio.h>
# include <stdio.h>
void calculations(int,int);
void main (int sum,int diff)
{
int num1,num2;
int * pointer1;
int * pointer2;
printf ("Enter num1: ");
scanf("%d",&num1);
printf ("Enter num2: ");
scanf("%d",&num2);
calculations(num1,num2);
pointer1 =∑
pointer2 =&diff;
printf ("The sum is : %d\n",pointer1);
printf ("The sum is : %d\n",pointer2);
getch();
}
void calculations (int num1,int num2)
{
int sum,diff;
sum = num1 + num2;
diff = num1 - num2;
}