Posted in podcasts

In this month’s episode of Wrong, But Useful, we’re joined by @DrSmokyFurby and his handler, Belgin Seymenoglu. Apologies for the poor audio quality on this call. Dave's fault, obviously1 . We discuss: The Talkdust podcast (via Adam Atkinson): Life insurance Superpermutations: new record for n = 7 in the comments

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Posted in puzzles

I had a fascinating conversation on Twitter the other day about, I suppose, different modes of solving a problem. Here’s where it started: Heh. You spend half an hour knee-deep in STEP algebra, solve it, then realise that tweaking the diagram a tiny bit turns it into a two-liner. —

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Posted in ask uncle colin

Dear Uncle Colin, If I didn’t have a calculator and wanted to know the decimal expansion of $\sqrt{2}$, how would I be best to go about it? Roots As Decimals - Irrational Constant At Length Hi, RADICAL, and thanks for your message! There are several options for finding $\sqrt{2}$ as

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Posted in dome

Stefan Banach was one of the early 20th century’s most important mathematicians - if you’re at all interested in popular maths, you’ll have heard of the Banach-Tarski paradox; if you’ve done any serious linera algebra, you’ll know about Banach spaces; if you’ve read Cracking Mathematics (available wherever good books are

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Posted in ask uncle colin

Dear Uncle Colin, I have to find the points $A$ and $B$ on the curve $x^2 + y^2 - xy =84$ where the gradient of the tangent is $\frac{1}{3}$. I find four possible points, but the mark scheme only lists two. Where have I gone wrong? I've Miscounted Points Like

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Posted in matrices

Every so often, I see a tweet so marvellous I can't believe it's true. Then I bookmark it and forget about it for months, until I don't know what to write next. An example is @robjlow's message from June: Aren't determinants wonderful? pic.twitter.com/vxIKeS4Lrq — Robert Low (@RobJLow) June 26, 2018

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Posted in ask uncle colin

Dear Uncle Colin, I'm told that $2^a \equiv 9 \pmod{11}$. How do I find $a$? - Powers And Stuff, Calculating And Learning Hi, PASCAL, and thanks for your message! As so often, there are (at least) two reasonable ways to tackle this: a brute force way and an elegant way.

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Posted in reviews

Sometimes, someone dies and you think “it’s a pity their time came.” And sometimes, someone dies and you think “oh no! We needed them.” Hans Rosling (for me) was in the second camp: someone using maths for social good, someone combining graphic design, storytelling and numbers to make the world

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Posted in ask uncle colin

A Hanging Rope Dear Uncle Colin, I'm designing a small cathedral and have an 80-metre long rope I want to hang between two vertical poles. The poles are both 50 metres high, and I want the lowest point on the rope to be 20 metres above the ground. How far

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Posted in podcasts

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 The Mind Camel Cup Qwinto Number of the podcast: Lucy doesn’t like numbers so we don’t have one. Does your collection of

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