# 47 (number)

47 is the natural number following 46 and followed by 48.

 Template:Numbers 40s Cardinal forty-seven Ordinal 47th (forty-seventh) Factorization prime Roman numeral XLVII Binary 0101111 Hexadecimal 2F

## In mathematics

Forty-seven is the 15th prime number, a safe prime, and the 8th Lucas number.

It is also a Keith number, because it recurs in a Fibonacci-like sequence started from its base 10 digits: 4, 7, 11, 18, 29, 47...

## References to 47

There exists a humorous 47 society at Pomona College, California, USA which propagates the (joking) belief that the number forty-seven occurs in nature with noticeably higher frequency than other natural numbers. The origin of 47 lore at Pomona appears to be a math proof, written in 1964 by Professor Donald Bentley, which supposedly demonstrated that all numbers are equal to 47.

Following on from this inside joke, Joe Menosky, who graduated from Pomona College in 1979 and went on to become one of the story writers of Star Trek: The Next Generation, "infected" other Star Trek writers with it, and as a result the number occurs in a subtle hidden way in almost every episode of this program and its spin-offs Star Trek: Deep Space Nine and Star Trek: Voyager. The number might be mentioned in the dialogue, it might appear on a computer screen a character is looking at, and it might be a substring of a larger number. The number also appears on some of the DVD menu screens for the episodes.

According to a (joking) statement by Rick Berman (the co-creator and executive producer of several Star Trek series), "47 is 42, corrected for inflation". The number 47 is referenced often in the television series Alias.

In 1998, Japanese electronic musician Takako Minekawa released the album Cloudy Cloud Calculator, which featured a song about the number 47 entitled Kangaroo Pocket Calculator. The song repeatedly states that "47 is a magical number. 47 plus 2 equals 49. 47 times 2 equals 94. 49 and 94. 94 and 49. Relationship between 47 and 2, is magic" and eventually concludes "Isn't it a coincidence?"

Forty-seven is also: