title: Windows form application c#
body: <p>I am designing a windows form application in c# visual studio.  for example i have three textboxes Textbox1 texbox2 and textbox3 i want that when user type a number (integer or float) in textbox1 it is automatically added to the values entered in textbox2 when he press enter and displayed in textbox3 .also texbox1 and 2  clears when the numbers are added in textbox3 , how can i do that ?? thanks in advance.  </p>
  
  <p><a href="https://i.stack.imgur.com/EXWob.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EXWob.png" alt="enter image description here"></a></p>