**It’s clearly a budget. It’s got a lot of numbers in it.**

‘Number stations’ are shortwave radio stations that broadcast streams of meaningless words, letters, tunes or Morse code. They follow a pattern: first, they repeat something recognisable that identifies the transmission (two bars from the folk song ‘The Lincolnshire Poacher’ is the most famous) followed by a string of 200 or more numbers.

Number stations appeared after the Second World War, but nobody knows who set them up or what for. They're thought to be ways of sending messages to spies, firstly because the messages have proven so far un-crackable. Secondly, by broadcasting them publicly there is no way of proving that someone has been listening them.

‘Arabic numerals’ were actually invented in India in the 5th century. They’re called ‘Arabic’ because Europeans learned about them via Arab traders from North Africa in the Middle Ages. Arab mathematicians know them as ‘Hindu numbers’. The concept of zero also originated in India in the 9th century, though the decimal point system is a 9th century Arab invention.

The new system took at least half a millennium to become established. In the 11th century, there were still at least three different types of arithmetic in the Arab world. The shapes we use for numbers today date from 13th century Marrakesh and are not the same as those used in modern Arabic. 1 and 9 look similar, but the Arabic number that looks like a slightly squashed 0 means 5 and a zero is just a dot.

Further confusion came with the gradual collapse of the Holy Roman Empire from 1453, when Roman numbers became known as ‘German’ numbers. The arrival of printing in the 15th century gave a boost to the new ‘Arabic’ numbering system, but Roman (or ‘German’) numerals continued to be used alongside them until the 17th century.

Roman numerals are often thought of as unwieldy and unsuitable for calculations but there are algorithms that enable them to be used for quite complex mathematics. When adding and subtracting, Roman numerals are actually slightly easier to use than Arabic ones: the sum 100+200=300 involves learning the meaning of four arbitrary symbols, whereas the same sum in Roman (C+CC=CCC) involves only one and seems more intuitive.

**Torture numbers and they’ll confess to anything. **

A '1' followed by 100 noughts is called a 'googol'. The word was coined in 1938 by an eight-year-old – specifically, by Milton Sirotta, the nephew of American mathematician Edward Kasner. A googolplex is a '1' followed by a googol noughts – or more noughts than there are atoms in the known universe.

These numbers are only really used to show the difference between big numbers and infinity – which is not a big number but a mathematical concept. The name of the search engine Google was taken after a researcher looked to see if 'googol' was taken as a domain name - it nicely summed up the projected size of the database. It was accidentally misspelled as 'google'.

Surprisingly, if you type 'GIMPS' into Google, the first result is for the 'Great Internet Mersenne Prime Search'. This is a project that's looking for enormous prime numbers by harnessing the power of many computers. New, large prime numbers are useful for encrypting data; in 1994 Roger Schlafly patented two very large prime numbers, which are used as part of a cryptographic method.

**All is number.**

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A fragment from the Book of Revelations that was discovered in 2005, revealed that the original number of the beast was 616, not 666.

The Electronic Frontier Foundation will award $200,000 to the first person to find a prime number with at least 1,000,000,000 digits.

Margaret Thatcher was offered passport number 007 but she turned it down.

In 2010, exactly the same numbers came up in the Israeli lottery twice in three weeks.

Four was usually written 'IIII' in classical Latin, not IV. The latter was mainly a medieval usage.

Four is the only number whose value is the same as the number of letters in its name.

The Mayans had the concept of zero by around 30 BC, at which time, Romans and Greeks didn’t bother with zero much. For Greeks, maths was geometry and zero made no sense in that context. For the Romans, nulla (‘nothing’) was used rather than a symbol.

It was the work of the Italian mathematician Fibonacci (who grew up in North Africa) that brought the symbol to Europe in the 13th century.

Between 1960 and 1977 the secret number authorising US presidents to launch nuclear missiles was 00000000.

Mathematician Alex Bellos conducted a survey to find the world’s favourite number. He had 30,023 respondents. The lowest whole number that nobody chose was 110, which makes it the world’s least-loved number; so QI has adopted it as our favourite.

According to Alex Bellos the most popular number is 7. This was borne out in the National Lottery draw of 23rd March this year. Five of the six numbers were multiples of seven (7, 14, 21, 35 and 42: the other was 41). So many people chose them, that there were more people who matched exactly 5 numbers than matched exactly 4. If you got four right you won £51 if you got five you won £15.

142,857 – Is known as a cyclic number. If you multiply it by any number between 1 and 6, you will always end up with an anagram of the original number:

142,857 x 2 = 285,714

142,857 x 3 = 428,571

142,857 x 4 = 571,428

142,857 x 5 = 714,285

142,857 x 6 = 857,142

but then something weird happens:

142,857 x 7 = 999,999

Forty is the only number in English that, when written out as a word, has its letters in alphabetical order.

The number of people who died taking a selfie in 2014 was 49.

The number of people who died from auto-erotic asphyxiation in 2014 was 625.