c# excel

I was putting together an Excel add-in with some User Defined Functions (UDFs), using C#. Based on excelDNA documentation, I created a class that checks to see if OPTIONAL Excel arguments are present in a UDF. And if not, it assigns a default value. I created a couple of simple test functions...

You can set formula like this in an excel file using c#: Worksheets("Sheet1").Range("A1").Formula = "=$A$4+$A$10"; If the formula contains '%' then an error occurs!!! (a table column name contains %) How can you use % in formula?