Fortytwo

Fortytwo is the natural number that follows forty-one and precedes forty-three. In decimal notation it is written as 42. It is an even, composite number with prime factorization 2 × 3 × 7, and it is a pronic number equal to 6 × 7. It is also a Harshad (Niven) number since the sum of its digits (4 + 2) equals 6, which divides 42, yielding a quotient of 7. The sum of its proper divisors is 54, making 42 an abundant number. In Roman numerals it is XLII, in binary 101010, and in hexadecimal 2A.

Fortytwo has become famous in popular culture due to Douglas Adams’ The Hitchhiker’s Guide to the Galaxy, where it is humorously described as the Answer to the Ultimate Question of Life, the Universe, and Everything, discovered by the computer Deep Thought after 7.5 million years of calculation. Since then, the number 42 has appeared in a wide range of media, science, and education as a cultural reference and puzzle motif.

In science and technology, 42 has several notable associations. It is the atomic number of molybdenum, a metal used to impart strength and heat resistance in steel alloys. In astronomy, Messier 42 (M42) is the Orion Nebula, a bright region of star formation. In computing, the ASCII code 42 corresponds to the asterisk (*) character, commonly used as a wildcard or multiplication symbol. The number also features in various mathematical and recreational contexts due to its simple factors and base-10 representation.