test.c

#include <stdio.h>
#include <stdint.h>
#include <inttypes.h>

uint64_t fact(uint64_t n);
int main()
{
  int t, n, r,i;
  scanf("%d",&t);
  for ( i =0 ; i < t ; i++) {
    scanf("%d %d",&n,&r);
    printf("%"PRIu64"\n",(uint64_t)(fact(n)/(fact(r) * fact(n-r))));
  }
  return 0;
}

uint64_t fact(uint64_t n)  {
  return (uint64_t)((n == 1 || n == 0) ? 1 : (n * fact(n-1)));
}