I used the regular expressions to check if a char is number.
I choose to use regular expressions than using the Double.TryParse() because I feel RegEx are faster then the TryParse function. I could be wrong but at this point is doing the job.
public string StripNumbers(string input)
Regex regEx = new Regex("[0-9]+");
StringBuilder sb = new StringBuilder();
foreach (char a in input)
The next steps will be to test performance and find out what method is faster to check for IsNumber().