Wrong, But Useful: Episode 15
podcasts/wbu15.mp3
It’s the (slightly delayed) monthly chat between @reflectivemaths (Dave Gale) and me on whatever maths has caught our eyes.
This month:
 Why protractors and set squares? You can find centres of rotation.
 Why constructions? Colin launches an impassioned defence and compares them to Killer Sudoku
 Dave has some great ideas for improving the Mathematical Instruments package, while Colin wants to shake up the calculator industry
 Exams: do you deserve full marks for a lucky guess? Neither of us think so, but the GCSE disagrees. Outrage ensues, before Dave suggests not ranting about exams yet again.
 Dave goes shopping for horseballs but only finds confusinglypriced pizza [link]. We fail to discuss the density of prawns. Colin suggests the reason is ‘economics’. Dave brushes this off. Dave is unhappy about the convention in some puzzles that A=1, B=2 and so on ((which I’m not going to typeset in LaTeX because it’s NOT ALGEBRA)) but Colin thinks he’s being oversensitive.
 Stephen Hawking lets the side down with a Perfect Formula. Even for charity, even with some actual statistics behind it, that’s a case for the Maths Police.
 Dave interrupts the football commentary with a superrelevant query: is half a million chickens a lot to rehome ((Possibly on the other side of the street.)) ?
 Colin’s reading: Dead Reckoning by Ronald Doerfler, which has inspired him to try to do 1/97 in his head (it’s 0.010309278350515463…  he could go on, but your calculator couldn’t.)
 The World Cup seeding system: how England, Holland and Italy managed to fall foul of it by picking silly friendly opponents.
 Dave interrupts the football commentary again to explain that that last month’s answer was $\frac{5}{11}$; gold stars to @srcav and @notonlyahatrack

This month’s World Cup puzzle:
How many possible World Cup tournaments are there? There are 32 teams in eight roundrobin groups (each with six games, each of which has three possible results) and 16 knockout games (each with two possible results). We’re not interested in the actual number: just how many digits long it is.
 Colin doesn’t understand Graham’s Number and isn’t really sure how to say ‘Knuth’
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* Updated 20140921 to fix a link.