using System; using System.Globalization; using System.Linq; using System.Collections.Generic; public class Test { public static void Main() { var listOfString = new List() { "full1","full1inc1","full1inc2","full1inc3","full2","full2inc1","full2inc2","full3","full100inc100" }; var isolatedList = listOfString .Select(str => "full" + new string(str.Reverse().TakeWhile(Char.IsDigit).Reverse().ToArray()));; foreach(string str in isolatedList) Console.WriteLine(str); } }