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// 写一个程序,要求输入一个数,求从这个说前面15个数开始计算和 //方法一: Console.Write("请输入一个数:"); int n = int.Parse(Console .ReadLine ()); int sum =0; for (int i = n - 15; i <= n; i++)//for (int i = n ; i >= n; i--) { sum = sum + i; } Console.WriteLine(sum); Console.ReadLine(); //方法二: Console.Write("请输入一个数:"); int n = int.Parse(Console.ReadLine()); int sum = 0; for (int i = 1; i <= 16; i++) { sum += n; n--; } Console.WriteLine(sum); Console.ReadLine();