Char.IsDigit and Char.IsNumber are both methods within the System namespace. The methods themselves are almost confusing in name at first glance. You might think that they do the same thing, but then why have both? Well, because they don't do the same thing. IsDigit refers to only the decimal digits whereas IsNumber can refer to anything in the numeric Unicode category. So, if you just want decimal, stick with IsDigit. Otherwise, you'll be getting a lot more than you bargained for if cleaning data...