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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Posted in podcasts

In this month’s thrilling installment of Wrong, But Useful, we’re joined by @c_j_smith, who is Calvin Smith in real life. We discuss… Number of the Podcast: 5 Are Fish and Chip shop owners good at maths? Two maths puns and a maths joke Are there ‘popular’ books that ‘lead you

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Posted in ask uncle colin

Dear Uncle Colin, Can there be two or more consecutive irrational numbers? - Between A Number And Consecutive… Huh? Hi, BANACH, and thanks for your message! We… have a problem here. When you’re dealing with integers, consecutive is really neatly defined: every number has a single successor, a number that’s

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Posted in puzzles

One of the many lovely things about Big MathsJam is that I’ve found My People - I’ve made several very dear friends there, introduced others to the circle, and get to stay in touch with other maths fans through the year. It’s golden. Adam Atkinson is one of those dear

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Posted in ask uncle colin

Dear Uncle Colin, I’m given that $0 \le x \lt 180^o$, and that $\cos(x) + \sin(x) = \frac{1}{2}$. I have to find $p$ and $q$ such that $\tan(x) = -\frac{p + \sqrt{q}}{3}$. Where do I even start? - Some Identity Needing Evaluation Hi, SINE, and thanks for your message! There

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