Lucky number 7

If you ask anyone to choose a number between one and ten, many times that person will choose lucky number 7. But why? Is it something about being larger than five, but just not quite being ten? Is it because seven ate nine? There are actually many reasons why the number seven is considered a lucky number, similar to the four-leaf clover, and none of them have anything to do with the number’s appetite. Spoiler alert: it’s more mathematical than superstition, believe it or not.
Why is 7 a lucky number?

There are the Seven Wonders of the World. The seven dwarfs. Seven days in a week. Seven colours in the rainbow. There are seven swans a-swimming. Seven notes on a musical scale. Seven deadly sins. The list goes on.
Some mathematicians and scientists believe that there are specific properties of the number seven that make it appealing to people. Alex Bellos, a mathematician and writer for The Guardian, set out to find the world’s favourite number in a massive, public vote on his website – which received more than 44,000 votes from numberphiles around the world.
Voters gave many reasons for their choices. Often, a number signified an important date, a memorable age, or simply exuded “friendliness and warmth.” Odd numbers outperformed evens, and round numbers ending in 5 or 0 proved too vague for most tastes (“When we say 100, we don’t usually mean exactly 100, we mean around 100,” Bellos says. “Why would you have something as your favourite that is so vague?”).
We like symmetry

In third place, number eight was rewarded for its lovely symmetry and associations with the Chinese character for prosperity. In second place, number three took the prize for its many appearances in culture and nature (as they say, everything is better in threes). And, with nearly 10 per cent of the total vote, the world’s favourite number according to Bellos’ poll is… seven.
Shocked? Probably not. It turns out that seven’s triumph only reaffirms a human fascination that goes back thousands of years. Bellos points out that ancient Babylonian tablets were riddled with sevens, an observation future historians might make about us when reviewing footage of casino slot machines and craps tables.