How to get Formula in excel from frontend using c# + vsto.

Hi All

I am working with Excel Addin.I am using Vsto 2013 and excel 2016 version as tools for the development.

I have to implement formula as one column in excel sheet.

Here we want to get the formula from the frontend using c#.

The problem here is that i am unable to get the formula at the particular cell where i gave some formula, rather than it is showing all the cells in the formula format only.