The Hitchhiker's number is equal to \(2^{267,709} \approx 2.748 \times 10^{80,588}\)[1]. It was coined in The Hitchhiker's Guide to the Galaxy, a comedy science fiction novel by Douglas Adams. Adams jokingly gave this number as the reciprocal of the probability that a spaceship would pick someone up in the cosmos during a period of 30 seconds.
The number contains exactly 80,589 digits, placing it just under a googolgong, and larger than \(6 \uparrow\uparrow 3\). This makes it small enough to compute and store the full decimal expansion on modern computers. The full decimal expansion of the number can be found at Hitchhiker's number/Decimal expansion.
Values[]
The Hitchhiker's Number has different values depending on which version of The Hitchhiker's Guide to the Galaxy it comes from.
- The original 1978 radio broadcast and the 1979 novel adaptation state the number to be \(2^{267,709} \approx 2.748 \times 10^{80,588}\).
- The 1981 TV series adaptation states the number to be \(2^{260,199} \approx 5.056 \times 10^{78,327}\).
- The 2005 feature film states the number to be \(2^{2,079,460,347} \approx 1.741 \times 10^{625,979,939}\).
Humorously, none of these are the value that this wiki page stated for at least 10 years, which was erroneously thought to be \(2^{276,709}\).
Approximations[]
These approximations are based on the old incorrect value of \(2^{276,709}\). Thus, this section needs to be updated.
| Notation | Lower bound | Upper bound |
|---|---|---|
| Scientific notation | \(5.117\times10^{83\,297}\) | \(5.118\times10^{83\,297}\) |
| Arrow notation | \(2\uparrow276\,709\) | |
| Steinhaus-Moser Notation | 5[3][3] | 6[3][3] |
| Copy notation | 7[7[5]] | 8[8[5]] |
| Taro's multivariable Ackermann function | A(3,276706) | A(3,276707) |
| Pound-Star Notation | #*((95))*135 | #*((96))*135 |
| BEAF | {2,276709} | |
| Hyper-E notation | E[2]276,709 | |
| Bashicu matrix system | (0)(1)[3] | (0)(1)[4] |
| Hyperfactorial array notation | (7!)! | (8!)! |
| Fast-growing hierarchy | \(f_2(f_2(14))\) | \(f_2(f_2(15))\) |
| Hardy hierarchy | \(H_{\omega^22}(14)\) | \(H_{\omega^22}(15)\) |
| Slow-growing hierarchy | \(g_{\omega^{\omega^4+\omega^214+\omega3+9}2}(16)\) | |
Sources[]
- ↑ Douglas Adams (1979), The Hitchhiker's Guide to the Galaxy, pp. 80