Did you know As early as 1500 B.C., the ancient Egyptians developed a sundial that was calibrated to divide the interval between sunrise and sunset into 12 parts. This system reflects their use of a duodecimal system. They used this system because it reflects the 12 lunar cycles in a year. They may also have used 12 because of the number of finger joints on each hand: three on each of the four fingers excluding the thumb, which made it easy to count to 12