# Wrong, But Useful: Episode 49

/podcasts/wbu49.mp3

In this month’s episode of Wrong, But Useful, Colin and Dave are joined by Special Guest Co-Host @pecnut, who is Adam Townsend in real life.

- Adam studies the behaviour of sperm in mucus, and chocolate fountains ((Not sperm in chocolate fountains, just chocolate fountains in general.)) - when he’s not editing @chalkdustmag - Issue 6 of which is available now from chalkdustmagazine.com, or from a @mathsjam near you - the magazine for the mathematically curious.
- Number of the podcast is . @colinthemathmo explains why here. More on truncatable primes here.
- Colin has a new book available, wherever good books are sold - which Dave has actually read some of and quite likes.
- @colinthemathmo has a @numberphile video on juggling. We reference an article about @standupmaths
- An orchestra of 120 players…, written by @LongmoorClaire (Claire Longmoor in real life). We mention a Radiolab episode and UCL’s Maths Choir
- Adam is an expert on chocolate fountains and needs blood.
- RIP Vladimir Voevodsky and his work (via @johncarlosbaez) and Monty Hall, mentioned in The Maths Behind, available wherever etc.
- Timothy Gowers’ write-up on the infinites thing we were talking about (via @johncarlosbaez)
- We almost caused @hnodrog to crash
- October is Black Mathematician Month.
- October also contained Ada Lovelace Day, of which more in future episodes.
- Next episode is our 50th and goes live around my 40th birthday: we are keen to have audio sent in to celebrate this, and to talk to people at Big MathsJam next month.
- A history of maths typography.
- Last Puzzle: A number has exactly three prime factors, and can be written as $129 \times 141 \times 147 + 320$. What is the sum of the three prime factors? It’s 417 ($131\times 137 \times 149$). Gold star to @chrishazell72.
- Puzzle, via @colinfoster77 - Prove the divisibility by 7 test (split off the last digit, double it and subtract it from what’s left.)