Set Theory Clock
If you saw this piece of technology every day, it would immediately make sense. On the other hand, if you aren’t familiar with it, this is probably nearly impossible to work out. It’s actually a “set theory clock” located in Berlin.
This type of clock tells time using increments of fives and ones, represented by yellow lights. The first row is hours (by fives), the second is hours (by ones), and the third and fourth rows repeat the pattern for minutes. This picture was taken at 11:41.