Top all-time · #4424
Possibly Wrong
Personal blog · possiblywrong.wordpress.commathscienceprogramming
Possibly Wrong is a personal blog at possiblywrong.wordpress.com about math, science and programming. Since 2013, 17 different Hacker News readers have linked it 23 times, most often “Using a Watch as a Compass”. It is still writing: the last post was on 2026-09-26, and you can follow it by feed.
Too few sampled comments (10) to say how often HN recommends it.?
Why HN links it
HN commenters link this blog for probability and maths posts: the Skittles duplicate-pack problem, the birthday paradox, using a watch as a compass, queueing theory and card shuffling.
Summarised by Claude from a sample of 10 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
On science, mathematics, and computing
Most-linked posts?
- Using a Watch as a Compass2 people · 3 mentions · first linked 2022-10-19
- I found two identical packs of Skittles among 468 packs2 people · 2 mentions · first linked 2019-04-17
What Hacker News says?
You could probably make it in a few minutes - the direction of the sun is, to a first approximation, 15 degrees times the number of hours it is after midnight. This leads to a trick for using an analog watch as a compass: https://www.citizenwatch-global.com/support/exterior/directi... https://www.watchaffinity.co.uk/blog/how-to-use-your-watch-a... This is more prone to errors closer to the equator and in the summer…
Comment linking /2012/01/25/using-a-watch-as-a-compass/
on “Show HN: I made a website to find best bus seat to avoid the sun while traveling”Submitted I found two identical packs of Skittles among 468 packs as a story · 826 points
HN discussionThe picture he shows of all the Skittles' counts looks like something I would've seen at the local museum. He missed his chance of taking an ultra high resolution photo of it and putting it on display: https://possiblywrong.wordpress.com/2019/04/06/follow-up-i-f...
Comment linking /2019/04/06/follow-up-i-found-two-identical-packs-of-skittles-among-468-packs-with-a-total-of-27740-skittles/
on “I found two identical packs of Skittles among 468 packs”Submitted Calories in, calories out as a story · 189 points
HN discussionAuthor of the article here; this is a great point. This experiment initially stemmed from a nice analytical solution to the problem of computing the expected value (via generating functions as described in the post). Computing other moments, let alone the entire distribution, required some Monte Carlo simulation, as shown at the end of the first article ( https://possiblywrong.wordpress.com/2019/01/09/identical-pac.…
Comment linking /2019/01/09/identical-packs-of-skittles/
on “I found two identical packs of Skittles among 468 packs”Submitted Lemonade Stand as a story · 129 points
HN discussionEssentially this means approximating the bearing of the sun X hours after midnight the sun as 15X degrees. This works better the closer to the poles you are and the closer to the winter solstice it is - see for example https://possiblywrong.wordpress.com/2012/01/25/using-a-watch...
Comment linking /2012/01/25/using-a-watch-as-a-compass/
on “How to use a watch as a compass”Submitted Analysis of adversarial binary search game as a story · 61 points
HN discussion0.1mm is not very smooth. According to wikipedia, 150 grit sandpaper has average particle size of 90-100µm edit: of course there is vigorous internet commentary about billiard ball smoothness compared to earth: https://possiblywrong.wordpress.com/2011/01/03/is-the-earth-... https://skeptics.stackexchange.com/questions/10763/is-earth-... https://billiards.colostate.edu/faq/ball/smooth/ Which mostly seem to agree that…
Comment linking /2011/01/03/is-the-earth-like-a-billiard-ball-or-not/
on “Kansas is Flatter Than a Pancake (2003)”Submitted The Fisher-Yates shuffle is backward as a story · 5 points
HN discussionIn a similar vein, I saw this linked from HN not too long ago and thought it was a really neat application of the birthday paradox--all about finding duplicate packs of Skittles: https://possiblywrong.wordpress.com/2019/04/06/follow-up-i-f...
Comment linking /2019/04/06/follow-up-i-found-two-identical-packs-of-skittles-among-468-packs-with-a-total-of-27740-skittles/
on “Birthday Paradox Revisited”Submitted Calories In, Calories Out (2014) as a story · 4 points
HN discussionI'm pretty sure there is some fundamental queueing theory to back this up, as it's the main takeaway I had from a queuing theory course I took in college. Can't remember the details though, so I'm not sure it would still apply if a single queue entailed long walks from the head of the queue to the nearest available 'processor'. EDIT: more background here https://possiblywrong.wordpress.com/2010/12/26/why-multiple-..…
Comment linking /2010/12/26/why-multiple-checkout-lines-are-not-all-bad/
on “Tracking traveler phones lets Cincinnati airport cut security line wait by third”Submitted If the Earth Were a Cube as a story · 4 points
HN discussionWhy? There are very efficient machine-learning-free solutions... There are even rote solutions a human can use n his own head with a bit of practice. The game is basically solved. https://possiblywrong.wordpress.com/?s=blackjack
Comment linking /?s=blackjack
on “Show HN: Blackjack Probabilities”Submitted String Art from Images as a story · 3 points
HN discussionAuthor of the linked article here; re marking movement of shadows, I wrote a follow-up that discusses some alternatives, mainly that one: https://possiblywrong.wordpress.com/2014/07/05/using-a-watch...
Comment linking /2014/07/05/using-a-watch-or-a-stick-as-a-compass/
on “Using a Watch as a Compass”Submitted Using a Watch as a Compass as a story · 2 points
HN discussionThe article deserves several clarifications: > The deck has to be cut more or less in half before shuffling. "More or less" is doing some heavy lifting here. The original GSR shuffling model cuts the deck at a point that is binomially distributed , so that for example about one-fifth of the time the cut may be at least as asymmetric as a 21-31 card split, which I think most would agree is nowhere near "the precision…
Comment linking /2018/09/02/arbitrary-precision-rational-arithmetic-in-c/
on “Seven Perfect Shuffles Randomize a Deck of Cards. But How Many Sloppy Ones?”Submitted Floating-point equality: It’s worse than you think as a story · 2 points
HN discussionSubmitted Beware the "Natural" Quaternion as a story · 1 points
HN discussionSubmitted There Is No Equilux as a story · 1 points
HN discussionSubmitted Counting possible positions in the board game Battleship, regular and hexagonal as a story · 1 points
HN discussion
