Posted in puzzles

Here’s a tweet from @colinthemathmo: Here's another one. Take a square, crease in the halfway mark, fold up a corner - where does the corner go to? What are its coordinates? pic.twitter.com/Bfr0X8ACur — Colin Wright (@ColinTheMathmo) February 12, 2018 I’m not big on origami, but if Colin thinks it’s an

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Posted in ask uncle colin

Dear Uncle Colin, I lost the first game of my Big Internet Math-Off tournament - can I still win the group and qualify for the semi-finals? - Surely Combinations Of Talent, Luck And Nous Deliver? Hi, SCOTLAND, and thanks for your message! Because the tie-break rules aren’t currently clear, I

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Posted in hypothesis testing, statistics

At an academic conference; 22 people in the room. Speaker asks who is a middle child. There is only one in the entire group - him. Striking (if anecdotal) confirmation of stereotypes about birth order. — Leigh Caldwell (@leighblue) December 14, 2018 As a loyal listener to More or Less,

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Posted in bimo2019

A quick extra post today: I’m in the Big Internet Math-Off, which decides who will become the World’s Most Interesting Mathematician of 2019. My first group match is today, against @kyledevans, and I’ve done a video for it! Go over to the Ap’, have a look at the pitches, and

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Posted in ask uncle colin

Dear Uncle Colin, If I know that $a+b+c = 0$, how can I show that $(2a-b)^3 + (2b-c)^3 + (2c-a)^3 = 3(2a-b)(2b-c)(2c-a)$? - Something You Might Merrily Explain? Thanks! Regards! Yippee! Hi, SYMMETRY, and thanks for your message! As usual, there are myriad ways to attack this, of which I

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Posted in dome

What are they? A Sophie Germain prime is a prime such that $2p+1$ is also prime - for example, 23 is a Sophie Germain prime since 47 is also prime. The largest known Sophie Germain prime has close to 400,000 digits; it is conjectured that there are infinitely many such

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Posted in ask uncle colin

Dear Uncle Colin How would you prove that $\cos(2x) > 1 - 2x^2$ for $x > 0$? - Can’t Obviously See It, Need Explanation Hi, COSINE, and thanks for your message! I’d start by noting that as soon as $x > 1$, the right hand side is smaller than -1,

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Posted in ranting

I grew up with Countdown as part of my diet. I had a crush on Carol Vorderman (before she went all advertisey and weird). I loved the numbers game, obviously – although I still have some slight resentment that Ian Scarrott was class champion rather than me. A few years

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Posted in ask uncle colin

Dear Uncle Colin, My six siblings and I have inherited a fortune of £$10^{10} + 10^{(10^2)} + \dots 10^{(10^{10})}$, to be divided evenly between us. However, we’re a very squabbly family, so we want to know how much money will be left over once it’s divided up. Can you help?

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Posted in ninja maths

“I beg your pardon?!” yelled the Mathematical Ninja. The terribly well-dressed gentleman stood his ground. “I said, sensei, I would work $0.8^{10}$ out differently.” A sarcastic laugh. “This, I have to see!” “Well, $8^{10} = 2^{30}$, which is about $10^{9}$.” “About.” “Obviously, we can do better with the binomial: $2^{10}$

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