How to auto populate textboxes based on entered value.

I m trying to populate a set of 3 textboxes based on a value entered into the first textbox. So when a user enters a value in the first textbox, i would like them to be able to tab out of it and it will automatically populate the remaining textboxes.
 
I know javascript has the OnBlur function which can do this but is there a way to accomplish this using asp.net (c#)
 
Thanks,   
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