# You're reading: Posts Tagged: prime numbers

### Small gaps between large gaps between primes results

The big news last year was the quest to find a lower bound for the gap between pairs of large primes, started by Yitang Zhang and carried on chiefly by Terry Tao and the fresh-faced James Maynard.

Now that progress on the twin prime conjecture has slowed down, they’ve both turned their attentions toward the opposite question: what’s the biggest gap between subsequent small primes?

### Primo: now a colourful, actual mathematical board game

Primo, a board game which puts the ‘fun’ in the fundamental theorem of arithmetic, has now been successfully funded via Kickstarter. In a recent blog post, the creators Katherine Cook and Daniel Finkel boast:

The game plays beautifully in play test after play test. It’s one of the most mathematically rich games we have ever seen, and at the same time avoids that icky “educational game” feel. Primo is a real game and it’s worth playing because it’s fun. Really fun.

It’s been a while since we’ve done one of these, but here’s a selection of Twitter accounts you may wish to follow. This week, the theme is numbers!

While I usually try to pull out an interesting tweet to showcase the brilliance of the accounts I recommend, in this case the account is tweeting every prime number. It’s run by an automated script, which you can see the code for, and according to its bio, aims to tweet “Every prime number, eventually”. Ambitious.

### Prime gaps update

There’s been some progress on the bounded gaps between primes front since we last checked in.

The Polymath8 project has got the gap down to $4,680$. But that’s small beans: James Maynard, a postgrad student at Oxford, announced at a meeting in Oberwolfach that he has got the gap down to $700$. Emmanuel Kowalski has written an effusive post on his blog singing the praises of Maynard’s achievement.

### Open Season: Prime Numbers (part 2)

In this short series of articles, I’m writing about mathematical questions we don’t know the answer to – which haven’t yet been proven or disproven. This is the third article in the series, and across two parts will discuss various open conjectures relating to prime numbers. This follows on from Open Season: Prime numbers (part 1).

So, we have a pretty good handle on how prime numbers are defined, how many of them there are, and how to check whether a number is prime. But what don’t we know? It turns out, quite a lot.

### Open Season: Prime Numbers (Part 1)

In this short series of articles, I’m writing about mathematical questions we don’t know the answer to – which haven’t yet been proven or disproven. This is the third article in the series, and across two parts will discuss various open conjectures relating to prime numbers.

I don’t think it’s too much of an overstatement to say that prime numbers are the building blocks of numbers. They’re the atoms of maths. They are the beginning of all number theory. I’ll stop there, before I turn into Marcus Du Sautoy, but I do think they’re pretty cool numbers. They crop up in a lot of places in maths, they’re used for all kinds of cool spy-type things including RSA encryption, and even cicadas have got in on the act (depending on who you believe).

### Cushing your luck: properties of randomly chosen numbers

Long-time Aperiodical muse David Cushing has made a bet with us that he can give us an interesting post every Friday for the next ten weeks. Every week that he sends a post, we buy him a bar of chocolate. Every week that he doesn’t send us a post, he buys us a bar of chocolate. For his first trick, David is going to do some unnatural things with the natural numbers.

The greatest common divisor (gcd) of two or more integers is the greatest integer that evenly divides those integers. For example, the gcd of $8$ and $12$ is $4$ (usually written as $\gcd(8,12)=4$). Two integers are called coprime (or “relatively prime”) if their gcd is equal to $1$.

A reasonable question to ask is,

Given two randomly chosen integers $a$ and $b$, what is the probability that $\gcd(a,b)=1$?