Are you a numberphile who also loves Douglas Adams? If so, then you probably already know where this is going ...

In this week's amusing video, we learn about all the quirky traits of the number 42. It was writer Douglas Adams who made this number famous in his book, The Hitchhiker's Guide to the Galaxy, as being the "Answer to the Ultimate Question of Life, the Universe, and Everything", according to one of the book's characters, the supercomputer, Deep Thought.

But more than being the meaning of life in nerd culture, 42 has a number of properties that really are interesting. First, 42 is a pronic number, which is defined as being the product of two consecutive integers, n (n + 1), as such:

6 × 7 = 42

In binary, 42 is represented by this handsome number; 101010

Also, in number theory, 42 is a primary pseudoperfect number such that, when the prime factors of the number are inverted and added to the inverse of the number itself, they add up to the number one:

so the first step is to find all the prime factors (p) that make up our number (N), which is 42, like this:

2 × 3 × 7 = 42

by substituting all the numbers -- our three different prime factors, p, and our original number, N -- into the above equation, we get:

1/2 + 1/3 + 1/7 + 1/42 = 1

This is a rare quality, shared by numbers 2 and 6, and then the size of the following primary pseudoperfect numbers after 42 rapidly become truly staggering in size.

Oh, and before I forget, 42 is the atomic number for the essential element, Molybdenum!

Here are several numberphiles telling us more about the amazing properties of the number, 42:

Visit numberphile's YouTube channel [video link].

Perhaps you would like to read Douglas Adams' The Hitchhiker's Guide to the Galaxy for yourself? [Guardian Bookshop; Amazon UK; Amazon US].

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Numberphile, the latest project by video journalist Brady Haran, is on facebook and can also be found on twitter @numberphile

In this video, we met:



Dr James Grime, a mathematics professor at the University of Cambridge

Dr Philip Moriarty, a physicist and expert on nanoscience at the University of Nottingham

Dr Gerardo Adesso, a Lecturer of Applied Mathematics at the University of Nottingham

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