How much is a pretty license plate worth, and what does that number measure?
Kind of knowledge: UnprovenNot enough evidence. Someone has claimed it, but no source or study is strong enough to confirm it. The five labelsThe short answer: people pay real extra money for numbers they believe are lucky, and pay less for numbers they believe are unlucky. In the Hong Kong license plate auction market, plates bearing the number 8 sold for noticeably higher prices, plates bearing the number 4 were clearly discounted, and number sequences that read as auspicious phrases in Cantonese also carried their own price levels. That price gap does not measure luck. It measures the money people are willing to spend on a belief, plus the portion paid for being seen to own something expensive.
Why are plate auctions an ideal measure of belief?
Plate auctions give researchers something rare: a public price, stated by buyers themselves, for an object with no material function beyond being seen. Travis Ng and colleagues set out four conditions for an asset to measure the value of belief: belief must be the determining factor of price, price must be observable over a long period, other price determinants must be controllable, and price must closely reflect underlying social value. License plates meet all four.
The key point is that buyers spend their own money. No one forces them to buy number 8. They choose between two plates identical in function, differing only in digits, and pay more for the one they prefer. That premium is the most honest declaration of the value they assign to the number.
Kind of knowledge: UnprovenNot enough evidence. Someone has claimed it, but no source or study is strong enough to confirm it. The five labelsIn Hong Kong, the government began auctioning plates in 1973 and is the sole body selling plates through public auction. Auctions are oral and ascending, with a starting price of HK$1,000 for ordinary plates, while special plates have starting prices set by the government. Each session sells over a hundred plates in succession, usually on weekends and around Lunar New Year.
Which numbers are paid more for, and which are paid less for?
Ng and colleagues published their results in the Journal of Economic Psychology in 2010, based on Hong Kong plate auction data from 1997 to 2008. The main finding: number 8 was paid a premium, number 4 was discounted, and the discount was statistically significant across all plate types.
A more interesting finding lies in how the premium changes with sequence length. For ordinary four-digit plates, number 4 was discounted by about 11 percent; for ordinary three-digit plates, that rose to 27.3 percent. For special plates, the discount increased from 15.6 percent at four digits, to 20.9 percent at three digits, 34.5 percent at two digits, and 83.2 percent at one digit. Number 8 followed the exact opposite direction: the fewer the digits, the larger the reward for number 8.
Kind of knowledge: School: Ng and colleaguesSchool's interpretation. How one school or one book reads it; other schools may read it differently. The five labelsThe authors' explanation is direct: when a sequence is shorter, each digit carries more weight in the plate as a whole, so the willingness to pay for an 8, or to avoid a 4, rises accordingly. They compare it to how one healthy year is worth more when the remaining lifespan is shorter.
| Plate type | Discount for number 4 | Source |
|---|---|---|
| Ordinary four-digit plate | 11% | Ng et al. 2010 |
| Ordinary three-digit plate | 27.3% | Ng et al. 2010 |
| Special four-digit plate | 15.6% | Ng et al. 2010 |
| Special three-digit plate | 20.9% | Ng et al. 2010 |
| Special two-digit plate | 34.5% | Ng et al. 2010 |
| Special one-digit plate | 83.2% | Ng et al. 2010 |
When the whole sequence reads as a phrase, how does the price change?
Chi-Keung Woo and colleagues published in 2008 in the Journal of Economic Psychology a separate study on willingness to pay for cultural signals in Hong Kong plate sequences. Unlike counting individual digits, this study considers the whole combination: a sequence can read as a meaningful phrase, and that meaning has its own price.
Ng and colleagues also tested this. The most favored combination was 168, which sounds close to the phrase "smooth sailing all the way" in Cantonese. After controlling for individual digits, plate 168 still sold at a much higher price: on average nearly three times that of plate 861, a combination that does not correspond to any meaningful phrase in Cantonese. The combinations 138, 813, 148 and 814, which sound close to "I will be rich all my life", were also associated with higher winning bids.
This result matters because it separates two layers of meaning. The first layer is each individual digit: 8 good, 4 bad. The second layer is the whole sequence as a phrase: 168 good, 861 neutral. Both layers carry a price, and the second cannot be fully reduced to the first.
Is the price gap just belief, or also status signaling?
Jia He and colleagues published in 2020 in Management Science a study on belief, conspicuous consumption and the housing market in Singapore. The results show a price gap tied to conspicuous consumption: buyers pay not only for the belief that a number brings luck, but also for others seeing them own that number.
This aligns with another observation in the Hong Kong auction data. Ng and colleagues noted that ordinary plates are not transferable, a rule meant to limit speculation, but there were still "clever" ways around it, such as selling all shares of the company owning the plate. In the first personalized plate auction, 210 plates were sold to 159 buyers; 143 bought only one plate for themselves, 16 bought more, and one bought as many as 22 plates, reportedly for trading. The existence of such a secondary market shows that pretty plates are valuable not only to end users, but also as an asset that can be bought and resold.
Does belief in numbers change with economic conditions?
Ng and colleagues tested the hypothesis that people believe in numbers more strongly when the economy is struggling. They used the Hang Seng Index at the end of the month in which the plate was auctioned as a proxy for the macroeconomic environment. The results show that the discount for number 4 was negatively correlated with the market index: when the market fell, the discount for number 4 rose. Specifically, for ordinary four-digit plates, the average discount for number 4 was -201.1% + 19.9% times the log of the market index; a 1 percent drop in the index raised the discount by 19.9 percent.
This is a noteworthy methodological finding. Kind of knowledge: School: Ng and colleaguesSchool's interpretation. How one school or one book reads it; other schools may read it differently. The five labelsThe authors state plainly that such belief is not based on reason, but the way it changes with the economic environment is consistent with economic intuition. In other words, even a belief with no material basis has measurable price behavior, and that behavior responds to external circumstances in predictable ways.
How should real effects born from belief be understood?
Kind of knowledge: School: Ng and colleaguesSchool's interpretation. How one school or one book reads it; other schools may read it differently. The five labelsOne layer needs to be made clear to avoid both extremes. Belief in numbers can produce real effects, but through an indirect mechanism: belief changes behavior, behavior changes outcomes. Ng and colleagues cite the phenomenon of cardiac death peaks among Chinese Americans and Japanese Americans, groups for whom number 4 carries a bad meaning, falling on the 4th of the month, a pattern not seen among white Americans. That effect, if real, is not because number 4 has supernatural power, but because the psychological stress caused by belief can influence the timing of a health event.
In other words, when belief changes behavior and behavior changes outcomes, we register that effect as a psychosocial one. That does not mean the number predicts destiny, nor does it mean denying the effect. The two are different and need to be kept separate.
Is there any evidence that a pretty plate reduces accidents or increases luck?
Kind of knowledge: UnprovenNot enough evidence. Someone has claimed it, but no source or study is strong enough to confirm it. The five labelsNo evidence in the studies cited above shows that a pretty plate reduces traffic accidents or brings real luck. These studies measure the market price of belief, not the effect of a number on the owner's life. The fact that a plate sells for a higher price only proves that buyers are willing to pay more for it, not that it brings anything beyond being owned.
What about Vietnam?
In the reference list of this article there is no study on license plate auctions in Vietnam. Vietnam does hold car plate auctions, but no academic work has been published in the list for comparison. If citing auction results in Vietnam from the press, one should use outlets with operating licenses and note the time frame of each session, because plate auction prices depend heavily on timing, plate type and current regulations.
It should also be noted that the results above all come from Hong Kong and Singapore data, on buyer groups in those markets, over the period 1997 to 2008 for the Hong Kong data. They should not be directly extrapolated to Vietnamese people without research on Vietnamese people. Vietnamese number culture has its own features, such as reading numbers by Sino-Vietnamese pronunciation and folk taboos different from Cantonese, so price levels and the ranking of numbers may differ.
How should these results be read correctly?
The three studies above belong to evidence level A: results published in specialized journals, with data and verifiable methods. They show that belief in numbers has a real market price, and that price includes at least two components: belief in what the number brings, and status signaling from owning it.
What these studies do not say is that numbers have supernatural power. They also do not say that people who pay high prices are uninformed. In the market, buyers pay for something they find valuable, and that value may lie in a sense of reassurance, in the pleasure of seeing a sequence they like, or in others seeing them own it. All three are real reasons for buyers, even if they do not sit in the same frame of reference as the question "does the number bring luck?"
For those interested in how numbers are calculated and what they mean in Eastern tradition, the article Eastern Numerology: How to Calculate and the Meaning of Numbers covers that separately. This article keeps only one point: when a belief about numbers enters the market, it leaves a measurable trace, and that trace is where researchers read the social weight of belief.
