# Daily LEGO: Ping Pong Ball Clock

Recently discovered (but apparently ten years old now), a fellow named Helge from Trondheim, Norway, built an awesome clock using LEGOs, Technics, and ping pong balls.

Every minute a fan starts up and blows a new ball from the reservoir at the bottom, through the long tube and up to the uppermost tray. This tray has room for two balls. When it is full, it tilts. One ball rolls onto the second tray, the other falls to the reservoir. Thus a new ball enters the second tray every two minutes. The second tray has room for 5 balls.
When it is full, it tilts. One ball rolls onto the second tray, the others fall to the reservoir. The third tray has room for 6 balls. Thus the three uppermost yellow trays count the minutes in an hour. Each ball in the uppermost tray counts for one minute, each ball in the second tray counts for 2 minutes, and each ball in the third tray counts for 10 minutes. If there is 1 ball in the uppermost tray, 2 in the second and 3 in the third, the time is
1+2×2+3×10=35 minutes past the hour.