How to Get a Column number in Excel by its Column name using C#

I created an Excel application using C# with MVVM model. In that excel I created some columns as template columns. For example I am having some columns like Unit, Cost and Quantity. Now I want to find the exact column number of "Quantity" .

How can i get that particular column(Quantity) number? can any one tell me some method to achieve this?

Thanks.

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