>>627
1.
#include <stdio.h>
int main(void)
{
int i, n;
double f = 1;
printf("input n: ");
scanf("%d", &n);
for (i = 1; i <= n; i++) f *= i;
printf("%d! = %.0f\n%d!/%d = %.0f\n", n, f, n, n, f / n);
return 0;
}

2.
#include <stdio.h>
int main(void)
{
int n;
printf("input n: ");
scanf("%d", &n);
if (0 <= n && n < 10) printf("●");
else if (10 <= n && n < 30) printf("○");
else if (30 <= n && n < 60) printf("△");
return 0;
}