MoMA Exclusive. There are passive clock watchers, and then there are those who are up for a little challenge. Keep your brain active and improve your mathematical skills with this clock, which digitally displays various math equations that need to be solved in order to read the time. For example, 8+4 hours and 30+3 minutes equals 12:33. Named after Albert Einstein, this time teller features a crisp white LED display and six different levels of difficulty. Can be set for 12- or 24-hour time. Wall-mountable. Includes power adapter.