/* Project Euler Problem 15 C# YOS G-spec */ /* http://odz.sakura.ne.jp/projecteuler/ */ using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { double ans=1,a=1,b=1; for (int i = 1; i <= 40; i++) { a*= i; } for (int i = 1; i <= 20; i++) { b*=i; } ans = a / (b * b); Console.WriteLine(ans); Console.Read(); } } }