Console.Write("請輸入一個100以內的整數：");
int shu =int.Parse(Console.ReadLine());
if (shu % 9 == 0)
Console.WriteLine("這是9的倍數");
if (shu / 10 == 9)
Console.WriteLine("他的十位是9");
if (shu % 10 == 9)
Console.WriteLine("他的個位是9");
if (shu % 9 == 1 && shu / 10 != 9 && shu % 10 != 9)
Console.WriteLine("這個數與9無關");
Console.ReadLine();