Developer[] developers = new Developer[] {
  new Developer { Name = "Paolo", Language = "C#", Age = 32 },
  new Developer { Name = "Marco", Language = "C#", Age = 37},
  new Developer { Name = "Frank", Language = "VB.NET", Age = 48 },
};

var developersGroupedByLanguage =
  from d in developers
  group d by new { d.Language, AgeCluster = (d.Age / 10) * 10 };

foreach (var group in developersGroupedByLanguage) {
  Console.WriteLine("Jazyk: {0}", group.Key);
  foreach (var item in group) {
    Console.WriteLine("\t{0}", item.Name);
  }
}
