An unlucky number is almost always a linguistic accident or a textual one, and the accident is usually traceable.
Four is feared across East Asia because it sounds like the word for death in Mandarin, Japanese and Korean. Italy avoids seventeen because of a Roman-numeral anagram. 666 was a coded reference to a Roman emperor, reached by gematria, the old practice of adding up the numeric values of the letters in a name. None of that is mysterious once you know the mechanism, and knowing the mechanism is more interesting than the shiver.
The pages under lucky numbers by culture take each tradition on its own terms. This one takes the five numbers people actually search for and gives each the same treatment: what the belief is, where it demonstrably came from, and what it has cost.
The two origin stories everyone repeats are the Last Supper, where Jesus was the thirteenth at the table the night before the crucifixion, and a Norse dinner in Valhalla that Loki crashed as the thirteenth guest, after which Balder died. Both are cited constantly and neither is well attested as the source. There is no record of the two being connected to an unlucky thirteen before the nineteenth century, which puts the folklore a long way after the fact.
The word itself is modern. Triskaidekaphobia first appears in English in Isador Coriat's Abnormal Psychology, published in 1911, which makes the vocabulary younger than the electric elevator that gave the superstition somewhere to live. Friday the 13th as a specific dread is younger still, and largely a twentieth-century American export.
The architectural consequence is the part people try to count, and the most-quoted number is softer than it looks. Dilip Rangnekar, a spokesman for Otis Elevator, told reporters that on the company's own installation records as many as 85% of the world's high rises have no floor labelled 13. Otis has never published that review, and the figure circulates in several versions that do not agree with each other. Treat it as one company's estimate rather than a survey. What is not in doubt is the practice itself: the button marked 14 opens onto the thirteenth storey, and nobody moved the concrete to get there.
As for whether the day is dangerous: a 1993 paper in the British Medical Journal by Scanlon and colleagues reported that the risk of hospital admission from a transport accident might be up to 52% higher on Friday the 13th. It is quoted everywhere and almost always without the authors' own caveat, which was that the number of accident admissions was too small to analyse meaningfully. Later studies found no effect.
Four is avoided across East Asia for one reason: it sounds like death. Mandarin 四 sì against 死 sǐ, Japanese 四 read shi against 死 shi, Korean 사 sa against the Sino-Korean 死 sa. The collision travelled with Chinese vocabulary into Japanese and Korean, which is why the same digit is dangerous in three languages and unremarkable in every language that borrowed nothing.
The avoidance is more thorough than the Western version of thirteen. Hong Kong towers skip whole bands: at some addresses the 39th floor is followed by the 50th, deleting every floor from 40 to 49. Lippo Mall in Jakarta labels its fourth floor 3A. Korail left locomotive number 4444 unassigned, and Korean hospitals, funeral halls and public buildings routinely skip the fourth floor, sometimes labelling the button F instead of 4.
It is not confined to Asia. Wynn and Encore in Las Vegas skip floors 40 to 49 for the same guests. Richmond Hill, Ontario banned the number 4 from new house numbering in June 2013, and Vancouver builders quietly omitted it until the city banned non-sequential numbering in October 2015.
There is even a claimed mortality effect, and it is a good example of why sourcing matters. Phillips and colleagues reported in the British Medical Journal in 2001 that Asian Americans were more likely to die of heart failure on the fourth of the month. Later work by Panesar and colleagues in Hong Kong, and separately by Gary Smith, found no statistical support for it. The honest summary is that the belief is real and the effect is not.
17
Italy's own number
Italy skips seventeen, not thirteen. The explanation given is a Roman-numeral anagram: XVII rearranges to VIXI, Latin for I have lived, which on a tombstone is a polite way of saying the occupant is finished. Whether that is the true origin or a later rationalisation is genuinely unclear, but the avoidance is not in doubt.
The consequences show up in product names and seat maps rather than in architecture. Renault sold the R17 in Italy as the R177. Alitalia aircraft had no row 17. Lufthansa carries neither row 13 nor row 17, and said in 2017 that it skips both because both are treated as unlucky, thirteen across much of the West and seventeen in Italy and Brazil. The dreaded date there is Friday the 17th, not Friday the 13th.
Thirteen goes the other way in Italy. Fare tredici, to make thirteen, means to strike lucky, and it comes from Totocalcio, the football pools, where predicting thirteen results correctly won the pot. The same digit that empties a Manhattan lift is a Neapolitan compliment.
666
The number of the beast
Revelation 13:18 gives the beast's number, and the standard text reads 666. Less well known is that it does not always. Papyrus 115, recovered from the rubbish mounds at Oxyrhynchus and held at the Ashmolean in Oxford, is the oldest surviving manuscript of Revelation, and it reads 616. Codex Ephraemi Rescriptus in Paris agrees with it.
Both numbers point at the same person. Written in Hebrew letters, Nero Caesar (נרון קסר) sums to 666; drop the final letter of the Latin form of the name, as a Latin speaker would, and the same name sums to 616. The number was a coded reference to a specific emperor, not a general-purpose curse.
The modern number still moves things. On 31 May 2003 the stretch of US Route 666 running through New Mexico, Colorado and Utah was renumbered US 491, after New Mexico's governor asked for the change; sign theft had been chronic and Navajo leaders argued the number was hurting tourism on tribal land. Arizona had renumbered its portion in 1992.
39
The Afghan taboo
The newest superstition on this page, and the most socially costly. In Afghanistan 39 reads as morda-gow, literally dead cow, which is established slang for a pimp. A car with 39 on its plate is not merely unlucky; it is an insult to the person driving it.
The market registered it immediately. A Kabul dealer told the Wall Street Journal he could buy a car cheaply because of the plate and resell it at a profit in a province where the association had not taken hold. Owners taped over the digits or reshaped the 3 into an 8. In January 2021, as Agence France-Presse reported, the Kabul traffic authority gave up and stopped issuing plates carrying the number at all.
Nobody can date the belief reliably. The usual account involves a pimp in Herat known by the number on his car, which has the shape of a story invented afterwards to explain something already in circulation. It spread through phone numbers and licence plates within a few years, which is a useful reminder that number taboos are not all ancient.
What an unlucky number actually costs
The measurable effects are all downstream of human decisions. Floors get renamed, so a building with forty storeys advertises fifty. Apartments on avoided floors sell at a discount, which means someone indifferent to the number gets a cheaper flat. Plates and phone numbers carrying a bad digit trade below the going rate, and the same numbers carrying a good one trade far above it.
What has never shown up is an effect on events. Every study claiming one has been contradicted by a better one, and the two most-cited papers both came with warnings from their own authors that the popular retelling ignores. The numbers people seek out behave no differently: eight in Chinese practice moves prices for the same homophone reason four does, and whether lucky numbers are real is the page that takes that question head on.
Unlucky numbers — frequently asked
13 has the widest reach, through Western Europe and the Americas. 4 has the deeper effect, because tetraphobia removes entire floor bands from buildings across East Asia rather than a single storey. Which one counts as most unlucky depends on whether you measure by how many people hold the belief or by how much it changes.
To make the upper floors easier to sell and let. It is a commercial decision rather than a superstitious one on the developer's part. A figure of 85% gets quoted constantly, but it traces to an Otis Elevator spokesman describing the company's own installation records, and Otis has never published the underlying review.
In most manuscripts, yes, at Revelation 13:18. But Papyrus 115, the oldest surviving copy of Revelation, reads 616, and so does Codex Ephraemi Rescriptus. Both numbers decode to Nero Caesar depending on whether you spell the name in Hebrew or in the Latin form, so the variant is a spelling difference rather than a contradiction.
No. Every study that appeared to find one has been contradicted by a larger or better-controlled follow-up: the 1993 Friday-the-13th accident paper carried its own warning that the sample was too small, and the 2001 finding on heart deaths and the fourth of the month failed to replicate in Hong Kong. What does hold up is the effect on prices and behaviour, which is a fact about people rather than about numbers.
No, it is specifically Italian. Most of Europe follows the thirteen convention.