>>3
問い１
#include <stdio.h>
int main(void)
{
int i;
double ans = 0.0;

for(i = 1; i <= 10; i++) ans += (double)i / ((i + 1) * (i + 2));

printf("%f\n", ans);

return 0;
}
問い２
#include <stdio.h>

int main(void)
{
int n;

scanf("%d", &n);

while(n != 1) {
if(n % 2 == 0) n /= 2;
else n = n * 3 + 1;
printf("%d\n", n);
}

return 0;
}