title: Generate unique number as image name
body: <p>I am a beginner with asp.net c#, started developing a website now stuck on image uploading form. I have to generate a unique number as a name of image and store the image in the images folder.How can i generate unique number of more than 2 digits in asp.net using c#. Unique number can also include letters.</p>
  
  <p>Any help is highly appreciated.
  Thanks!</p>