42
42 is a composite number, even, a calendar year.
In Douglas Adams' The Hitchhiker's Guide to the Galaxy, 42 is the answer computed by the supercomputer Deep Thought to the Ultimate Question of Life, the Universe, and Everything.
Mathematically, 42 is a sphenic number (the product of three distinct primes: 2 × 3 × 7), a pronic number, an abundant number, and the third primary pseudoperfect number. In 2019, mathematicians at the University of Bristol and MIT found a representation of 42 as a sum of three cubes:
\(42 = (-80\,538\,738\,812\,075\,974)^3 + 80\,435\,758\,145\,817\,515^3 + 12\,602\,123\,297\,335\,631^3\)
It was the last number under 100 for which such a representation was unknown.
Propriétés
Primalité
Prime factorization: 2 × 3 × 7
Diviseurs et multiples
Représentations
- En lettres
- forty-two
- Ordinal
- 42nd
- Chiffre romain
- XLII
- Binaire
- 101010
- Octal
- 52
- Hexadécimal
- 0x2A
- Base64
- Kg==
Aussi vu comme
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 42, here are decompositions:
- 5 + 37 = 42
- 11 + 31 = 42
- 13 + 29 = 42
- 19 + 23 = 42
As an ASCII codepoint, 42 is *. Printable ASCII character *.
As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.42.
- Address
- 0.0.0.42
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.0.42
Unspecified address (0.0.0.0/8) — "this network" placeholder.
This passes the ABA routing number checksum and matches the Federal Reserve numbering scheme.
Banks operate many routing numbers per state and division; an unmatched checksum-valid number can still be a real RTN at a smaller institution.