# Those 7-Sided UK 50 Pence Coins **URL:** \ **Category:** Factual Questions\ **Created:** [January 9, 2010, 8:13pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317 "2010-01-09T20:13:39Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [January 9, 2010, 8:13pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/1 "2010-01-09T20:13:39Z")
Do they work in vending machines? I always liked the 7-sided coins. also, the square coins in Aruba-are they a problem for vending machines? ---
**Author:** ![Mr\_Shine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mr_shine/32/464_2.png) [@Mr\_Shine](https://boards.straightdope.com/u/Mr_Shine)\ **Post date:** [January 9, 2010, 8:14pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/2 "2010-01-09T20:14:59Z")
Yes ---
**Author:** ![Baron\_Greenback](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/baron_greenback/32/48_2.png) [@Baron\_Greenback](https://boards.straightdope.com/u/Baron_Greenback)\ **Post date:** [January 9, 2010, 8:19pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/3 "2010-01-09T20:19:16Z")
Yes to the first question. I’ve no idea about Aruba. ---
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [January 9, 2010, 8:22pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/4 "2010-01-09T20:22:07Z")
The bag of ready-salted Walkers I had about 30 minutes ago can attest to the fact that 50ps do indeed work in vending machines. ---
**Author:** ![Baron\_Greenback](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/baron_greenback/32/48_2.png) [@Baron\_Greenback](https://boards.straightdope.com/u/Baron_Greenback)\ **Post date:** [January 9, 2010, 8:25pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/5 "2010-01-09T20:25:02Z")
Why do you think that they wouldn’t work in vending machines? ---
**Author:** ![Ximenean](https://avatars.discourse-cdn.com/v4/letter/x/aca169/32.png) [@Ximenean](https://boards.straightdope.com/u/Ximenean)\ **Post date:** [January 9, 2010, 9:00pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/6 "2010-01-09T21:00:56Z")
Because he apparently doesn’t realise that you can look things up on Wikipedia and Google, and learn about them. ---
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [January 9, 2010, 9:01pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/7 "2010-01-09T21:01:45Z")
> [@Ximenean](#): > > Because he apparently doesn’t realise that you can look things up on Wikipedia and Google, and learn about them. You can also ask actual humans on message boards. Which tends to be more efficient. ---
**Author:** ![Baron\_Greenback](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/baron_greenback/32/48_2.png) [@Baron\_Greenback](https://boards.straightdope.com/u/Baron_Greenback)\ **Post date:** [January 9, 2010, 9:08pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/8 "2010-01-09T21:08:01Z")
> [@Lobsang](#): > > You can also ask actual humans on message boards. Shit, you guys are actual humans? Fuck! :eek: ---
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [January 9, 2010, 9:11pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/9 "2010-01-09T21:11:26Z")
> [@Baron\_Greenback](#): > > Shit, you guys are actual humans? Fuck! :eek: Yeah, I was shocked too when I first found this out 😃 ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [January 9, 2010, 9:17pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/10 "2010-01-09T21:17:02Z")
Haah! They think we’re human. Then our disguises must be working. Tell John Big Boote quickly. ---
**Author:** ![zelie\_zelerton](https://avatars.discourse-cdn.com/v4/letter/z/59ef9b/32.png) [@zelie\_zelerton](https://boards.straightdope.com/u/zelie_zelerton)\ **Post date:** [January 9, 2010, 9:25pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/11 "2010-01-09T21:25:52Z")
Nah, we’re just bots pretending to be humans. Vending machines generally work by weight, not shape. So if an object is inserted which weighs about the same as a pre-designated coin-weight then the value of that coin will be credited. Hence why people bother to [counterfeit coins](http://news.bbc.co.uk/1/hi/england/kent/8415033.stm) - a metal pole is worth little but if you cut it up small…£££ ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 9, 2010, 9:32pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/12 "2010-01-09T21:32:00Z")
The UK 50p and 20p coins are both curves of constant width - that is, each side is an arc centred on the opposite corner - this helps them not to jam in any chutes or channels in vending machines or other coin mechanisms. (and the coin measures the same diameter no matter which way it falls through) > **[Curve of constant width](https://en.wikipedia.org/wiki/Curve_of_constant_width)** > > In geometry, a curve of constant width is a simple closed curve in the plane whose width (the distance between parallel supporting lines) is the same in all directions. The shape bounded by a curve of constant width is a body of constant width or an orbiform, the name given to these shapes by Leonhard Euler. Standard examples are the circle and the Reuleaux triangle. These curves can also be constructed using circular arcs centered at crossings of an arrangement of lines, as the involutes of c ---
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [January 9, 2010, 9:38pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/13 "2010-01-09T21:38:42Z")
> [@Mangetout](#): > > The UK 50p and 20p coins are both curves of constant width - that is, each side is an arc centred on the opposite corner - this helps them not to jam in any chutes or channels in vending machines or other coin mechanisms. (and the coin measures the same diameter no matter which way it falls through) > > [Curve of constant width - Wikipedia](http://en.wikipedia.org/wiki/Curve_of_constant_width) There you go. If the OP had simply googled the question instead of asking on a Message Board. I and possibly several others would not have been presented with the opportunity to learn something interesting today. ---
**Author:** ![gaffa](https://avatars.discourse-cdn.com/v4/letter/g/e68b1a/32.png) [@gaffa](https://boards.straightdope.com/u/gaffa)\ **Post date:** [January 9, 2010, 9:41pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/14 "2010-01-09T21:41:11Z")
> [@Mangetout](#): > > The UK 50p and 20p coins are both curves of constant width - that is, each side is an arc centred on the opposite corner - this helps them not to jam in any chutes or channels in vending machines or other coin mechanisms. (and the coin measures the same diameter no matter which way it falls through) > > [Curve of constant width - Wikipedia](http://en.wikipedia.org/wiki/Curve_of_constant_width) This answer is a great example of why asking a question on the Dope is better than just doing a search - that some piece of fairly esoteric knowledge will show up later in the thread that will be more interesting than the original question. It answers the unasked question of “why seven sides”. A square coin seems to remain troublesome. ---
**Author:** ![Ximenean](https://avatars.discourse-cdn.com/v4/letter/x/aca169/32.png) [@Ximenean](https://boards.straightdope.com/u/Ximenean)\ **Post date:** [January 9, 2010, 9:44pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/15 "2010-01-09T21:44:21Z")
> [@Lobsang](#): > > You can also ask actual humans on message boards. > > Which tends to be more efficient. Come on, this particular poster has a record of asking easily Googleable questions. One suspects that some people just like starting threads for the sake of it. I don’t see how it is more “efficient” for a load of other people to point you to Wikipedia et al, when you could just do it yourself. ---
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [January 9, 2010, 9:48pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/16 "2010-01-09T21:48:16Z")
> [@Ximenean](#): > > Come on, this particular poster has a record of asking easily Googleable questions. One suspects that some people just like starting threads for the sake of it. I don’t see how it is more “efficient” for a load of other people to point you to Wikipedia et al, when you could just do it yourself. I said tends to be. And by that I mean, on average you tend to get the answer to your question much quicker and more specifically by asking people, than by entering search terms into an artificially ‘intelligent’ computer system. Also the humans will often know of a resource better than Wiki for the subject matter. I get much better quality help, and quicker, when I use the Dope for computer programming related questions than when I google them. Google tends to present you with reams and reams of irrelivant information. It’s like looking for a particular needle in a stack of needles. Whereas asking the question to people is like asking people a question: They’ll probably tell you the answer. ETA: I am speaking generally. Does this OP have a habit of asking simplistic questions? I didn’t know. My main point is that Using Human beings as a resource is generally better than using Google or Wiki. How would you ask Wiki “Do those seven sided coins work in vending machines?” Wiki doesn’t understand questions worded like that. ---
**Author:** ![Ximenean](https://avatars.discourse-cdn.com/v4/letter/x/aca169/32.png) [@Ximenean](https://boards.straightdope.com/u/Ximenean)\ **Post date:** [January 9, 2010, 9:56pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/17 "2010-01-09T21:56:53Z")
It depends on the question. Questions like “how come non-circular coins, such as the British 50p, work in vending machines?” are readily and comprehensively answered with no human intervention. You just type “50p” into the Wikipedia search box. ---
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [January 9, 2010, 10:01pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/18 "2010-01-09T22:01:46Z")
> [@Ximenean](#): > > It depends on the question. Questions like “how come non-circular coins, such as the British 50p, work in vending machines?” are readily and comprehensively answered with no human intervention. You just type “50p” into the Wikipedia search box. And get a large article about the history and lots of other aspects of the British 50p, the whole article possibly not even mentioning vending machines. (Maybe it does mention vending machines and even answers the question. The point is, if you have a specific question such as the one in the OP and your choices are… \*seek out articles about one of the objects in the question and hope that by reading through the article eventually you’ll find a bit that answers your question \* and… _Go to a forum and ask. Someone there probably knows the answer already._ The second makes more sense. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 9, 2010, 10:08pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/19 "2010-01-09T22:08:50Z")
I can’t believe there’s an argument happening about _asking questions_ in a forum named ‘General Questions’. What is the problem? ---
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [January 9, 2010, 10:10pm UTC](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317/20 "2010-01-09T22:10:33Z")
Neither can I. And I’m one of the people arguing 🙂 [Next page](https://boards.straightdope.com/t/those-7-sided-uk-50-pence-coins/524317.md?page=2)