Friend of the site and good writer/bad drawer Ben Orlin has recently released a new book, and we were kindly sent a copy to play with and review.

## You're reading: Blackboard Bold

### Searching for the truth

Earlier today, I tweeted about my exciting new Pi search website, which lets you search for any string of digits within the infinite decimal expansion of π. If you haven’t seen it, go and check it out now.

### Mobile Numbers: Truchet Tiling

*In this series of posts, Katie investigates simple mathematical concepts using the Google Sheets spreadsheet app on her phone. If you have a simple maths trick, pattern or concept you’d like to see illustrated in this series, please get in touch.*

Since apparently I’m now a maven for interesting fun things built using Google Sheets, someone tagged me in to suggest I might like to see this Truchet Tiling Generator, built in Google Sheets using images generated in Google Drawing.

### The Mathematics of Spirograph

If you’re the kind of person who’s interested in doodling and/or fun toys, you might have encountered the fun doodling toy Spirograph, or some unbranded equivalent. It sits somewhere on the continuum between an artistic drawing tool and a neat mathematical gadget.

### Mathematically Gifted

Between the three Aperiodical editors (myself, Christian Lawson-Perfect and Peter Rowlett), there’s a developing tradition of excellent mathematical gift-giving. This year, Christian has excelled himself by designing and creating a brilliant mathematical hoodie, which features a meme about an in-joke (and who can resist either a meme or an in-joke?)

### Equatum puzzles – a chat with Justin Roughley

Equatum is a new puzzle format invented by mathematician Justin Roughley, and is now available in the form of a book. We chatted to Justin about his life and his puzzles.

### Mobile Numbers: Hitomezashi Stitching

*In this series of posts, Katie investigates simple mathematical concepts using the Google Sheets spreadsheet app on her phone. If you have a simple maths trick, pattern or concept you’d like to see illustrated in this series, please get in touch.*

It’s been a while since we’ve had an entry in this column, but the other day I was sent a link to a very interesting spreadsheet (which I, of course, opened using the Google Sheets app on my phone). The initial view was a pleasing pattern of squares, in two colours: