In this tutorial i am going to explain about how to create simple mathmatical captcha in asp.net c#.net and vb.net. The basic idea is generating two numbers using random function and storing the addition of that two numbers in the session and also converting the numbers into image using the available libraries. On the target page where the captcha is implemented we will have the textbox to get the input from the user and check the textbox value is equal to the session value. It it is equal then we consider the user is a human else it is a robot. In my previous article i have explained about Visual Studio Keyboard Shortcuts , How To get data from WEB API , How To Create Your First WEB API Project , Check Container Exists In Azure Blob , Convert Datatable To Json Data Array , How To Show Tooltip On Mouse Hover In Gridview and many articles in C#.Net , VB.Net , Grid View , Javascript , jQuery , SQL Server and many other topics. Here to explain the process i have created an empt...