Evaluating string expression. ex: "2+3"

double D= (double)new System.Xml.XPath.XPathDocument
(new StringReader("")).CreateNavigator().Evaluate
(string.Format("number({0})", new
System.Text.RegularExpressions.Regex(@"([\+\-\*])")
.Replace(TextBox1.Text, " ${1} ")
.Replace("/", " div ")
.Replace("%", " mod ")));

TextBox2.Text = D.ToString();


Note: Above will evaluate expression in Textbox1.Text