using System.Collections.Generic;
public static void Main()
var list = new List<Fake>(){ new Fake(){Age = 10}, new Fake(){Age = 10}, new Fake(){Age = 20}};
var ageCounts = from fake in list
group fake by fake.Age into g
foreach(var count in ageCounts){
Console.WriteLine(count.Age +":" +count.Count);
public int Age {get; set;}