How young are the members of f(x)?

How old are the members of f(x) and who is the youngest among them?

We know the real numbers here, but what does the app say?  Check out the next picture where Amber exclaimed, "WHAT THE HELL AM I 4?!?! #llamaproblems"~

This photo was taken during their shoot, and Sulli wasn't there.

♥ More of f(x) Amber's updates here

Credits:
Jieun,Amber's Instagram