Posted in decision maths, ranting

A student asks: How do you remember the difference between Prim’s algorithm and Kruskal’s algorithm? In honesty, I don’t. This is one of the things that REALLY FRUSTRATES me about D1: it puts so much emphasis on remembering whose algorithm was whose1 ahead of figuring out how to program computers

Read More →Note: this post is only about arithmetic and quadratic sequences for GCSE. Geometric and other series, you're on your own. Quite how the Mathematical Ninja had set up his classroom so that a boulder would roll through it at precisely that moment, the student didn't have time to ponder. He

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Posted in puzzles

One of my favourite sources of puzzles at the moment is @WWMGT - What Would Martin Gardner Tweet? (Martin Gardner, in case you’re not up on the greats of popular maths writing, was one of the greats of popular maths writing - and is indirectly responsible for Big MathsJam.) Recently,

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Posted in podcasts

A very short episode of WBU, as @reflectivemaths is moving house.

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Posted in ninja maths

So, there you are, stuck on a desert island, you've played your eight pieces of music, burnt the Bible and Shakespeare, and now you're kicking yourself for not bringing a calculator as your luxury item. An emergency has broken out and it's vital for your to work out $3^{0.7}$ as

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Posted in mechanics 1

This piece was entirely rewritten 2017-06-20 in response to a correction by Adam Atkinson. A friend of a friend stated: "... the planets exert an enormous influence on the tides..." ... and that set my oh-no-they-don't-o-meter. Let's have a look, shall we? You might think - as I did when

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Posted in gcse

A student asks: Why do you multiply by 1.07 if you're adding 7%? I thought 7% was 0.07. You're quite right - 0.07 is exactly the same thing as 7% (and, if you like, $\frac{7}{100}$). However, if you're adding on 7%, you need to multiply by 1.07, and here's why.

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Posted in gcse

A student asks: When you've got a value to the nearest whole number, why is the upper bound something $.5$ rather than $.4$? Doesn't $.5$ round up? So I don't have to keep writing something$.5$, let's pick a number, and say we've got 12 to the nearest whole number. $12.5$

Read More →An occasional series highlighting common errors that refuse to die. “It just… won’t stay dead!” he said, as the Mathematical Zombie moved closer. “$(a+b)^2 = a^2 + b^2$”, it said. “Brains! $(a+b)^2 = a^2 + b^2$.” “But… it doesn’t!” he said. “You have to multiply out the brackets!” “$(a+b)^2 =

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