Want to generate unique number in windows forms

Question

Dear friends,

I want to generate a unique number which increments for ex 123 with a combination of characters like for ex KN123 where only the digits should increment for ex the next unique number should be KN124 like that.. And at form load and after entry for that unique number and for the next entry it should show the next unique number .. how do i do that please tell me...

Thanks in advance.