title: Generate Unique ID following a specific pattern like "digitStringDigit" in C#
body: <p>I have earlier generated unique ids by making use of Math.Rando,  method or sometimes by using GUID.NewGUID method. This time I am trying to generate a unique numbers which are based on a specific pattern.</p>
  
  <p>for instance 123ABC123 - the length of the number will always remain 9 and it will contain 3 numeric digits followed by three characters and then followed by three more digits.</p>