# Wrong, But Useful: Episode 34

In this month's podcast, @reflectivemaths and I discuss:

• Colin's book being available to buy
• Number of the podcast: Catalan's constant, which is about 0.915 965 (defined as $\frac{1}{1} - \frac{1}{9} + \frac{1}{25} - \frac{1}{49} + ... + \frac{1}{(2n+1)^2} - \frac{1}{(2n+3)^2} + ...$). Not known whether it’s rational. Used in combinatorics and is $\int_0^\infty \arctan(e^{-t}) \dt$
• Chalkdust magazine Issue 3 is out, and the crossnumber is good. Colin and @christianp have cross-checked their answers using Elaborate Codes. Dave attempts to mock Colin for enjoying maths, and is fighting a losing battle.
• Dave has been reading about Tupper's Self-Referential Formula,
$\frac{1}{2} < \left \lfloor \left( \left \lfloor \frac{y}{17} \right \rfloor 2 ^{-17 \lfloor x \rfloor - \lfloor y \rfloor \pmod { 17 }} \right) \pmod { 2 } \right \rfloor$
• Dave came across Iva Sallay's Find The Factors game. It's good!
• Colin refers to Twynam's law, and gets Dave to admit that we should be suspicious about Statistics.
• @notonlyahatrack points us at the Romanian football team's venture into more interesting shirt numbers:

• @peterrowlett points us at @stecks's article about @rachelrileyRR's EE advert. (For clarity, as my speech isn't as clear as it might be: the article is by Katie alone, not by Katie and Peter.)
• Dave's students largely missed an answer in "solve $3x^2 = 147$". Colin thinks it's a bit of a gotcha.
• Relatively Prime Series 3 didn't reach its Kickstarter goal, and will not happen.
• @peterrowlett asks us to reveal the secret that Colin writes books. Colin erroneously states that Cracking Mathematics is out soon; it has been delayed until August, for no reason under Colin's control.
• Gold star for @chrishazell72, who identified that the church in Dave's last puzzle required 81 cards.
• This month's puzzle: given an equilateral triangle, what is the probability that a point inside the triangle lies closer to the centre than to any point on the edge?
• We congratulate ourselves on doing a good show and then Dave Hansens up the ending.

* Edited 2016-04-01 to clarify authorship of the Aperiodical article.
* Edited 2016-11-18 to correct a typo.

## Colin

Colin is a Weymouth maths tutor, author of several Maths For Dummies books and A-level maths guides. He started Flying Colours Maths in 2008. He lives with an espresso pot and nothing to prove.

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##### Where do you teach?

I teach in my home in Abbotsbury Road, Weymouth.

It's a 15-minute walk from Weymouth station, and it's on bus routes 3, 8 and X53. On-road parking is available nearby.