Add project files.

Helpers/StringExtensions.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Globalization;
+
+namespace Helpers
+{
+    public static class StringExtensions
+    {
+        public static bool IsNumeric(this string s)
+        {
+            return float.TryParse(s, NumberStyles.Float | NumberStyles.Integer, CultureInfo.CurrentUICulture, out _);
+        }
+    }
+}