c# dictionary keys to list

List<string> listOfKeys = theDictionary.Keys.ToList();

Dictionary<string, string> dicNumber = new Dictionary<string, string>();
List<string> listNumber = new List<string>();

dicNumber.Add("1", "First");
dicNumber.Add("2", "Second");
dicNumber.Add("3", "Third");

listNumber = dicNumber.Select(kvp => kvp.Key).ToList();
// Or:
listNumber = dicNumber.Keys.ToList();