Earlier this year, when getting the train to work was still *a thing* for me, I noticed this statistic:

# You're reading: Posts By Christian Lawson-Perfect

### The permutation clock

I recently had an idea: map the Unix time (seconds since 1st January 1970) to shufflings of a deck of cards. Each second would correspond to a different ordering of the 52 cards.

I wanted to think about how mind-bogglingly huge $52!$ is: $52!$ seconds is more than $2 \times 10^{60}$ years. So even if you spent your entire life watching this thing, you’d leave this world having seen basically none of the possible permutations. Happily, Wikipedia reckons that the heat death of the universe will happen in about $10^{100}$ years, so there’s plenty of time for me to enact my plan.

### Aperiodical Round Up 11: more than you could ever need, want or be able to know

Hello, my name’s Christian Lawson-Perfect and my main mathematical interest is “everything”.

Before The Aperiodical existed as its own thing, the only outlet I had for my mathematical eclecticism was a series of posts on the Acme Science blog called Aperiodical Round-Up. Eventually I stopped writing them, as work and family took up more of my time. This post has been sitting in The Aperiodical’s drafts folder for six years. Time to finish it!

Let’s begin with the first 10,000 digits of π dialled on a rotary phone.

### The Big Lock-Down Math-Off, Match 26

Welcome to the twenty-sixth and final match in this year’s Big Math-Off. Take a look at the two interesting bits of maths below, and vote for your favourite.

Here are today’s two pitches.

### The Big Lock-Down Math-Off, Match 24

Welcome to the twenty-fourth match in this year’s Big Math-Off. Take a look at the two interesting bits of maths below, and vote for your favourite.

You can still submit pitches, and anyone can enter: instructions are in the announcement post.

Here are today’s two pitches.

### The Big Lock-Down Math-Off, Match 22

Welcome to the twenty-second match in this year’s Big Math-Off. It’s back for one last gasp! Take a look at the two interesting bits of maths below, and vote for your favourite.

You can still submit pitches, and anyone can enter: instructions are in the announcement post.

Here are today’s two pitches.

### The Big Lock-Down Math-Off, Match 21

Welcome to the twenty-first, and possibly final, match in this year’s Big Math-Off. Take a look at the two interesting bits of maths below, and vote for your favourite.

You can still submit pitches, and anyone can enter: instructions are in the announcement post.

Here are today’s two pitches.