VS 2010 Date of Birth - Automatic age input

Hi. This one is pretty much the same as my last one, but im not sure how i can add it to this one.

When i add a date of birth into a masked textbox, how can i get it so it also adds the age of the person in a seperate textbox for me.

Example:


Masked textbox: 16/05/1992 (Adds the age '20' ---->) Textbox: 20


Thanks