Expert Dot Net

using System;

using System.Linq;

using System.Collections;

using System.Collections.Generic;

public class LINQDemo3 {

    public static void Main() {

        int N = 5;

        IEnumerable<int> intSequence = Enumerable.Range(1, N);

        foreach (int item in intSequence)

            Console.WriteLine(item);

        int agg = intSequence.Aggregate((av, e) => av * e);

        Console.WriteLine("{0}! = {1}", N, agg);

    }

}