Facts about numbers

Why are floors 4 missing in the east?

In China, Korea and Japan, the number 4 is considered unlucky, as it is consonant with the word "death". In these countries, floors with numbers ending in four are almost always absent.

Why is there no 13th floor in houses in some countries?

Due to the fear of the number 13, in many countries, the houses do not have the 13th floor (after the 12th there is immediately the 14th), or they are designated differently, for example, 12A or M (the 13th letter of the alphabet).

How do Arabs write and read numbers?

The Arabs use their own characters to write numbers, although the Arabs of Europe and North Africa use the familiar "Arabic" numbers. However, whatever the signs of numbers are, the Arabs write them, like letters, from right to left, but starting with the least significant digits. It turns out that if we meet familiar numbers in the Arabic text and read the number in the usual way from left to right, then we will not be mistaken.

How many times has the Sportloto Grand Prize been won?

Throughout the history of the Soviet Sportloto lottery, all 6 out of 49 numbers have been guessed correctly 3 times.

How many flowers should you give European girls?

In the United States, Europe and some eastern countries, it is believed that an even number of flowers given brings happiness. In Russia, it is customary to bring an even number of flowers only to the funeral of the deceased. In cases where there are many flowers in a bouquet, the evenness or oddness of their number no longer plays such a role.

How to check the authenticity of a euro banknote by the serial number?

The authenticity of a euro banknote can be verified by its serial number of the letter and eleven digits. It is necessary to replace the letter with its ordinal number in the Latin alphabet, add this number with the rest, then add the digits of the result until we get one digit. If this number is 8, then the bill is genuine. Another way to check is to add the numbers in a similar way, but without the letter. The result of one letter and number must correspond to a specific country, since the euro is printed in different countries. For example, for Germany it is X2.

How many legs do centipedes have?

A centipede doesn't have to have 40 legs. Centipede is the common name for different types of arthropods, scientifically combined into a superclass of centipedes. Different types of millipedes have from 30 to 400 legs and above, and this number may be different even in individuals of the same species. In English, there are two names for these animals - centipede ("centipede" in translation from Latin) and millipede ("milipede"). Moreover, the difference between them is significant - the milipedes are not dangerous to humans, and the centipedes bite very painfully.

Where did the Olympic Games take place with five-digit year marks?

On the emblems of the Olympic Games, the year is usually indicated by two (for example, Barcelona-92) or four numbers (for example, Beijing 2008). But once the year was marked with five digits. This happened in 1960, when the Olympics were held in Rome - the number 1960 was written as MCMLX.

What are the odd names of the numbers 70, 80 and 90 in French?

In most European languages, the names of numbers from 20 to 90 are formed according to a standard pattern - consonant with the base numbers from 2 to 9. However, in French, the names of some numbers have a strange logic. Thus, the number 70 is pronounced 'soixante-dix', which translates as' sixty and ten ', 80 is' quatre-vingts' (' four times twenty '), and 90 is' quatre-vingt-dix' ('four times twenty and ten "). The situation is similar in the Georgian and Danish languages. In the latter, the number 70 literally translates as "halfway from three times twenty to four times twenty."

Which world famous corporation name is the result of a spelling error?

When Larry Page and Sergey Brin came up with the name of the new search engine, they wanted to express in it a huge amount of information that the system is capable of processing. A colleague suggested the word "googol" - this is how mathematics refers to a number of one followed by a hundred zeros. He immediately checked the domain name for availability and, finding that it was free, registered it. Moreover, he made a mistake in spelling the word: instead of the correct 'googol.com' he entered 'google.com', but Larry liked the newly invented word and established itself as a name.

On satellite images of which Ukrainian city can you see the number 666?

In the 522 microdistrict of Kharkov, according to the plan, a block of residential buildings was to be built so that from the air they would form the letters of the USSR. However, after the construction of the three letters C and the vertical bar of the letter P, changes were made to the plan. As a result, these houses can now be seen as the number 666.

What mathematical distribution of numbers will allow you to check the reliability of financial data?

There is Benford's mathematical law, which states that the distribution of the first digits in the numbers of any dataset from the real world is uneven. The numbers from 1 to 4 in such sets (namely, birth or death rate statistics, house numbers, etc.) in the first position are found much more often than the numbers from 5 to 9. The practical application of this law is that it can check the accuracy of accounting and financial data, election results and much more. In some US states, inconsistency with Benford's law is even formal evidence in court.

Why is the name of the number 40 knocked out of the same type of names "twenty", "thirty", "fifty", etc.?

In Russian, the names of numbers up to 100, divisible by 10, are formed by adding the name of the number and "ten": twenty, thirty, fifty, etc. An exception to this series is the number "forty". This is explained by the fact that in ancient times the conventional unit of trade in fur skins was a bunch of 40 pieces. The fabric in which these skins were wrapped was called "forty" (the word "shirt" comes from the same root). Thus, the name "forty" supplanted the more ancient "four deste".

What is the optimal number of social connections for a person?

English anthropologist Robert Dunbar has identified a relationship between the size of the neocortical cerebral hemispheres of primates and the size of their flocks. Based on these data, he determined the optimal size of social ties for a person - 150. This number is confirmed in various historical periods and locations: for example, this is the estimated number of inhabitants of a Neolithic settlement or the size of the base unit of the Roman army. In 2010, Dunbar began researching the social network Facebook and came to the conclusion that his number is valid there too: despite the fact that some people have hundreds and thousands of friends on social networks, the average person is able to effectively interact with no more than 150 contacts.

Why does the numbering of trolleybuses in Budapest start from number 70?

Trolleybuses appeared in Budapest in 1949. The first trolleybus was immediately given number 70, since this year was the 70th anniversary of Stalin. And now there are no trolleybuses up to number 70 in Budapest.

Why did Pope John XX never exist, even though there were John XXI, XXII and XXIII?

Portuguese Pedro Julian was elected Pope in 1276 and took the name John. However, although the previous John bore the 19th serial number, this pope omitted one number and declared himself John XXI. He believed that a mistake had crept into the list of his predecessors, and there was an extra John in the history of the papacy. Later it turned out that he was mistaken, and there was no mistake, but the numbering could no longer be reversed. Therefore, it so happened that John XX never existed, although today the list of John ends with number XXIII.