Whats the logic behind the output

Question

Why does the following code prints 64 for i and 4 for j.

#include<stdio.h>
#define sqr(a) a*a
void main()
{
    int i;
    i=64/sqr(4);
    int j=64/16;
    printf("%d\n",i);
    printf("%d",j);
}

Output shown below