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In this month’s installment of Wrong, But Useful, Dave and I are joined by @honeypisquared, who is Lucy Rycroft-Smith in real life.

We discuss:

- Mathematical board games, including
**Number of the podcast**: Lucy doesn’t like numbers so we don’t have one.- Does your collection of maths people exclude anyone?
- Lucy went to Big MathsJam this year. Bowled over by the time taken to make sure people felt included. Clearly an intentional, thoughtful approach.

- Is stats actually maths
^{1}?- Reference to Sara Hottinger – Inventing The Mathematician

- Christmas books:
- Colin – Factfulness by Hans Rosling
- Lucy – Perils of Perception by Bobby Duffy
- Dave – The Indisputable Existence of Santa Claus by Hannah Fry and Thomas Oleron Evans
- Some deserved applause for @fryrsquared’s Zeeman medal and @stecks’s appearance on QI

- Via Adam Atkinson – Money Box. £35 000 per year for life or £480 000 now?
- The great makeup heist
- Postal systems and nutri-grain
- Quick bits:
- New largest Mersenne prime: $2^{82,589,933} − 1$. Prizes listed here for any Mersennaries out there.
- via @christianp: Plouffe’s prime-generating function
- via @chrishazell72 – Sibahle Zwane ‘answers complex arithmetic questions in seconds’ (Is he as good as the article seems to think?)
- via @fenneklyra: Follow up on “Guess who”: There are 24 people on board, and I had a typo, the first question narrows it down to 12 which means it IS the most efficient one cause you will always have narrowed it down by half. Not sure it’s allowed
- via @peterrowlett: Thirdsday
- via @christianp: A lot of mathematical mortality recently – including Jean Bourgain, Peter Swinnerton-Dyer, Elias Stein and Sir Michael Atiyah.
- via @peterrowlett and @robeastaway: Rotationally symmetric equations. See also here and here
- via @fermatslibrary: Pizza

**Puzzle feedback**: @schwartstack and Adam Atkinson both found answers in the region of $3.5 \times 10^{38}$, rather than quadrillions. Gold stars all round. On looking into it more, the Fantasy Flight Games site claims 104 septillion (still several orders of magnitude too small.)**This month’s puzzle**: Prove that 3 times the sum of 3 squares is the sum of 4 squares.**This month’s second puzzle**: A parent buys a pack of 24 candles. On their first child’s first birthday, they use one candle; on the second, two candles and so on. At some point, a younger sibling arrives, and the candles are used in the same way. On one of the first child’s birthdays, the parent finds they have exactly the right number of candles left for that birthday. How old is the first child, and how old were they when their younger sibling was born?

* Edited 2019-01-15 to fix some of the links. Thanks to Adam Atkinson for pointing out the error.

- QTWTAIN [↩]

## Adam Atkinson

http://1000000-euro.de/how-much-does-a-million-pounds-weigh/ is what you used during the recording?