Put your thumb on thumb impression mark, keep it there till it gets scanned and then it'll display some random results. Human age could not be calculated by iPhone devices yet to this date, so anyone believing the results to be true is a fool, just use this app to make one out of your friends :).
Age Scanner is a free high tech futuristic fingerprint scanner that attempts to determine how old you are based on your thumb print scan. Simply place your thumb on the scanning pad, wait for the scan and calculation to complete, and see what the app thinks your age is!
Age Scanner is for entertainment purposes only, and does not actually scan your finger print for real. That would be impossible.