1. Touch 'start'
2. The numbers 3 then 2 then 1 will pop up on the screen. Immediately following the number 1, several numbers will flash on the screen for barely one second.
3. Memorize the numbers' position on the screen, then click the circles from the smallest number to the largest number. It will flash an X if you are out of order.
4. At the end of game, the computer will tell you in years, how old your brain is.
Sounds complicated but it's really easy. Think fast.