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Tag: maths

  • Dan, a white man with a blue ponytail, wearing a green t-shirt, watches a stopwatch timer on his phone while filling a measuring jug from the kitchen sink.

    Β£4,803.40 a Year for Water?

    When we moved house, Thames Water failed to set us up an account correctly, and the hacky workaround they came up with claims that we spent our first 11 hours in the Chicory House perhaps pouring three tonnes of water into an ankle-depth 5Γ—10 metre swimming pool.

    Read more - about 5 minutes (1018 words)

    • Article
    • 3 comments
    • posted 30 April, 2026
  • Paper-based sketch showing an 'unwinnable' deck of 'five suit' FlopFlop, formed by stacking the cards in a strict reverse order to make it as hard as possible.

    FlipFlop Solitaire's Deck-Generation Secret

    I enjoy a mobile game called FlipFlop Solitaire, which provides a few thousand pre-seeded decks that are guaranteed "winnable". This blew my mind for a little while - how can you be sure that these shuffles are all winnable? But then I worked out a way to achieve exactly that result... by thinking in reverse!

    Read more - about 7 minutes (1458 words)

    • Article
    • posted 18 April, 2026
  • Pie charts approximating the probability of rolling 1-3, 4-5, 6, or 'multiple 6s' when rolling 1 through 8 six-sided dice.

    Visualising Forged In The Dark probabilities

    Blades in the Dark (and other Forged In The Dark-based games) use a highest-value-from-D6-dice-pool mechanic to resolve actions. I was looking for a visualisation of the resulting probabilities, but couldn't find one... so I made my own.

    Read more (353 words)

    • Article
    • 3 comments
    • posted 7 January, 2026
  • Turtle-graphics illustration of a yellow window made of four rectangular quarters, with a triangular mountain peak visible through it with its peak at the centre of the window.

    How I Learned the Pythagorean Theorem

    I clearly remember the day I first learned the Pythagorean theorem, because I had a problem I wanted to solve and a practical application that I wanted to use it on. Let's re-create the experience, and see if I can take any lessons about how to support my kids in their own mathematical journeys.

    Read more - about 4 minutes (871 words)

    • Article
    • 1 comment
    • posted 13 November, 2025
  • I'm looking at a listing for a ΒΌ" to ⅝" screw adapter, for which the seller warns that I should "please allow 1-3cm error".

    A 3cm error would mean that a ⅝" screw could result in a screw thread anywhere between 1β…˜" and... minus half an inch, I guess? (I don't even know how to make the concept of negative lengths fit into my brain.)

    I suppose this seller could send me an empty envelope and declare that it contained an infinitesimally small adapter. At which point... I'd be the one that was screwed!

    Full image of Highlighted item description from an eBay listing. The highlighted section shows that the listing is for a quarter inch to a five-eighth of an inch adapter made of a premium aluminium alloy, and that the buyer should "please allow 1-3cm error due to manual measurement".
    Alt

    Highlighted item description from an eBay listing. The highlighted section shows that the listing is for a quarter inch to a five-eighth of an inch adapter made of a premium aluminium alloy, and that the buyer should "please allow 1-3cm error due to manual measurement".

    • Note
    • posted 1 October, 2025
  • Sometimes people connect my unusual name to popular culture. They say things like "Oh, Q like James Bond?" or "Oh, Q like Star Trek?".

    I think their choice of franchise tells me more about them than they learn from my answer, which is usually "No, Q like the set of rational numbers."

    • Note
    • 3 comments
    • posted 28 September, 2025
  • Academic bibliography, citing six papers related principally to probability. The third paper, highlighted for the picture, is: Lobachevsky, "Analytic and Algebraic Topology of Locally Euclidean Metrizations of Infinitely Differentiable Remannian Manifolds" (Unpublished)

    Do you know the story of how Tom Lehrer hid an Easter Egg in an academic paper he wrote at the NSA, and his joke wasn't discovered for almost six decades?

    Read more (313 words)

    • Repost
    • of this original
    • posted 29 July, 2025
  • Build Colors from Colors with CSS Relative Color Syntax

    Caleb Hearth wrote an inspiring piece about CSS's new OKLCH functions, and now I want nothing more than to (re-?)implement something using this colour model!

    Read more - about 3 minutes (500 words)

    • Repost
    • of this original
    • posted 7 November, 2024
  • Graph using Hero's method to converge a series of gradually-improving gueses on 10 as the square root of 100.

    Hero of Alexandria

    Hero of Alexandria is my hero. And it's not for the steam engine he didn't invent (that was Vetruvius), nor for his formula for the area of a triangle, nor even for his programmable robot (yes, really). It's for his square root algorithm.

    Read more - about 4 minutes (877 words)

    • Article
    • posted 31 October, 2024
  • A 'full set' of white polyhedral dice commonly-used by roleplayers - a D4, D6, D8, two D10s, a D12, and a D20 - sit half-submerged in a red liquid.

    D20 with Advantage

    D&D players spend a lot of time rolling D20s. Sometimes they 'roll with advantage' - that is, roll two dice and take the largest. Last night I dreamed I derived the probability matrix for such rolls, and it got me thinking... could you construct a single die that rolls 'D20 with Advantage'?

    Read more - about 4 minutes (813 words)

    • Article
    • posted 12 September, 2024
  • Screenshot showing Sisyphus carrying a rock up a long numbered gameboard; he's on square 993 out of 1000, but (according to the rules printed below the board) he needs to land on 1000 exactly and never roll a double-1 or else he returns to the start.

    Sisyphus: The Board Game (Digital Edition)

    I implemented a terrible digital version of a truly stupid board game idea. My excuse is illness, I guess?

    Read more (174 words)

    • Article
    • 39 comments
    • posted 21 November, 2022
  • Dan sitting in the driving seat of a car, doing maths on a portable whiteboard.

    Mathematics of Mid-Journey Refuelling

    Dan uses the Secretary Problem to work out which filling station to pull over at for the cheapest fuel on a long journey.

    Read more - about 3 minutes (581 words)

    • Article
    • 1 comment
    • posted 27 May, 2022
  • Image representing post: Here’s What a Googol-to-One Gear Ratio Looks Like

    Here’s What a Googol-to-One Gear Ratio Looks Like

    Jason Kottke reports that Daniel Bruin has built a machine that demonstrates a truly absurd gear ratio, and Dan does some silly back-of-napkin maths.

    Read more (84 words)

    • Repost
    • posted 15 March, 2020
  • Image representing post: Who finished second?

    Who finished second?

    Nick Berry shares an amazing maths/logic puzzle, and Dan encourages you to give it a go for yourself.

    Read more (208 words)

    • Repost
    • posted 27 February, 2020
  • Image representing post: This equation will change how you see the world

    This equation will change how you see the world

    Veritasium's latest video looks at the patterns of order and chaos in fractals, and Dan thinks it's surprisingly good.

    Read more (48 words)

    • Repost
    • posted 12 February, 2020

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