There are various cases in which you may want to display results from aggregate functions (Sum, Avg, Count, Min, Max) performed over the columns in the grid in their footer. This post explains how to display aggregate functions in ASP.NET MVC Razor views.
Used Environment for this post: VS 2015 Update 3, ASP.NET MVC 5
For ASP.NET Web Forms, Read following post:
Displaying Total in ASP.NET Gridview Footer Row Without using Template Field