Fatto generale: 30 is the consumption in pounds of candy annually per person in Denmark, the country with the highest candy consumption.
Fatto matematico: 30 is the sum of the first four squares, which makes it a square pyramidal number.
Trivia: 30 is the number of uprights that formed the Sarsen Circle at Stonehenge, also the supposed number of holes forming the arrays of Y and Z Holes at Stonehenge.
Data storica: January 30th is the day in 1703 that the Forty-seven Ronin, under the command of Ōishi Kuranosuke, avenge the death of their master.