[00:00] i am taking this physical money into that physical&nbsp; sainsbury supermarket because in order to test a&nbsp;&nbsp; mass theory i need to find some combination of&nbsp; items that when i buy them the selfch checkout&nbsp;&nbsp;
[00:15] will give me a 50 p coin in my change here we&nbsp; go so i can buy a oxford exam set for £450 and&nbsp;&nbsp;
[00:27] we can examine what the soft checkout's going&nbsp; to do okay here we are a cash and card going&nbsp;&nbsp; to scan this barcode on the back okay notes&nbsp; in it in my change will come out out of here
[00:49] wipes there's my£5 note my change 220s two fives&nbsp; what the heck sainsburries four coins when one&nbsp;&nbsp;
[01:02] would do we have a perfectly good 50p coin here in&nbsp; the uk we have one and two pence coins 5p 10p 20p&nbsp;&nbsp; 50p and then 1 pound and two pound which i'll be&nbsp; referring to as 100 and 200 for consistency sake&nbsp;&nbsp;
[01:17] above that it's a£5 note now of those eight coins&nbsp; for some reason the sainsbury soft checkouts do&nbsp;&nbsp; not have 50p or 10p coins you can spend them&nbsp; but the coins you put in go into a different&nbsp;&nbsp;
[01:33] bucket they're not reused to give change to&nbsp; someone else all new coins have to be loaded&nbsp;&nbsp; in for change purposes and they don't put in tens&nbsp; they don't put in 50s so your worst case scenario&nbsp;&nbsp;
[01:45] if you should get a 50p coin you get four coins&nbsp; instead two 20s and two fives that's three more&nbsp;&nbsp; coins than you need if you need to get a 10p coin&nbsp; in your change you'll get two 5p coins that's one&nbsp;&nbsp; extra one but they don't combine because 60p you&nbsp; just get 320s so worst case scenario you can get&nbsp;&nbsp;
[02:03] up to three more coins in your change for the&nbsp; same value of change and just out of curiosity&nbsp;&nbsp; i knocked a little bit of code together to&nbsp; take every conceivable value below 500 and&nbsp;&nbsp;
[02:19] then across all of them average the number of&nbsp; coins you would get and in normal use across&nbsp;&nbsp; all eight coins you expect to get on average&nbsp; 4.6 coins in your change because sainsburries&nbsp;&nbsp; are using two fewer you get on average 5.9 coins&nbsp; in your change that's over an entire extra coin&nbsp;&nbsp;
[02:38] it's ridiculous and we'll get to why sainsburries&nbsp; are doing that later and it's not good but given&nbsp;&nbsp; i'd put together some code that could test&nbsp; the effectiveness of different combinations&nbsp;&nbsp;
[02:52] of coins i thought i'd see if i could do an anti-&nbsp; sainsburries what if we wanted to add a coin to&nbsp;&nbsp; make things better all right give me one second&nbsp; i'm just going to knock a quick coin together
[03:21] all right there it is i've just struck a 1&nbsp; 33 coin this is the coin the uk is missing&nbsp;&nbsp; so here's what i did i took the standard eight&nbsp; coins and then i added one more coin for every&nbsp;&nbsp;
[03:37] possible value between 1 and 499 and then&nbsp; averaged how many coins you get in change&nbsp;&nbsp; assuming all values between 1 and 499 below&nbsp; the note are equally likely and here's the&nbsp;&nbsp;
[03:49] plot of the average number of coins for every&nbsp; possible value we could add into the mix and&nbsp;&nbsp; there actually there are two two optimal points&nbsp; two local minimums that are 133 and 137 i assume&nbsp;&nbsp;
[04:02] the general public will be more open to a 1&nbsp; and a3 pound coin as opposed to a 1.37 pound&nbsp;&nbsp; coin but either one you add it in and the average&nbsp; number of coins in your change is now a mere 3.9&nbsp;&nbsp;
[04:16] that's under four that's an improvement&nbsp; but can we do better oh you know we can
[04:33] i'll make sure i get the eight up the right way&nbsp; don't get me started on eights that are up the&nbsp;&nbsp; wrong way makes me angry so matt why did you have&nbsp; to move office uh beats me why they didn't want me&nbsp;&nbsp; as an office mate so forget the 1.33 coin instead&nbsp; we're going to add a 77 p coin and we're going&nbsp;&nbsp;
[04:53] to add a184 coin and with these combined with the&nbsp; eight we already have it brings the average number&nbsp;&nbsp; of coins you get in your change down to 3.6 come&nbsp; on and we can keep adding coins the at this point&nbsp;&nbsp;
[05:07] i'm like you know what eventually we're just going&nbsp; to have one coin per value and it'll be an average&nbsp;&nbsp; change of one coin because there's 499 of them&nbsp; at some point you got to say look we can't just&nbsp;&nbsp;
[05:20] keep adding coins maybe eight is already too&nbsp; many what if we just replaced more of the ones&nbsp;&nbsp; we've already got it didn't take much to alter my&nbsp; code so instead of adding every possible coin to&nbsp;&nbsp;
[05:32] all eight it would take every subset of seven so&nbsp; like remove all the possible coins one at a time&nbsp;&nbsp; actually except for the one p coin we need that&nbsp; well we need that we'll get to that in a moment&nbsp;&nbsp; but we do need it if we want penny accuracy&nbsp; so it took each of the other seven out one at&nbsp;&nbsp;
[05:48] a time tried every possible replacement and your&nbsp; optimal improvement is to get rid of the£1 coin&nbsp;&nbsp; and replace it with a123 coin now i'm not going&nbsp; to belt that out of metal partly because it's&nbsp;&nbsp;
[06:00] super loud and fun fact we've had a complaint from&nbsp; someone in a nearby office but also because just&nbsp;&nbsp; replacing the one pound with the 123 brings the&nbsp; average down from 4.6 to around about 4.2 but we&nbsp;&nbsp;
[06:14] can do better because i just left the code going&nbsp; it started again and checked if there was another&nbsp;&nbsp; replacement that would be even better and another&nbsp; one that would be even better it turns out there&nbsp;&nbsp; are three more as well as£1 becoming 123 you can&nbsp; get rid of the two the 10 and the 50p coins and&nbsp;&nbsp;
[06:30] replace them with a 13 a 37 and an 88 pence coin&nbsp; and now your average number of coins in change is&nbsp;&nbsp; down to 3.9 we're back under four we haven't had&nbsp; to add any we just got to replace them and i was&nbsp;&nbsp;
[06:43] like wait a minute is that the best there's an&nbsp; interesting point here though because my search&nbsp;&nbsp; of finding what one swap is optimal at any point&nbsp; in time doesn't actually let you search all the&nbsp;&nbsp;
[06:55] possible solutions because you can't just change&nbsp; a coin in isolation it depends on the other ones&nbsp;&nbsp; so what you need to do is look at whole new sets&nbsp; because you don't just like choose a coin when&nbsp;&nbsp; you're giving change on its own it depends what&nbsp; other coins are available so you need to change&nbsp;&nbsp;
[07:10] all of them at once to find the global solution&nbsp; and thankfully someone who's better at programming&nbsp;&nbsp; than me has done just that i believe the optimal&nbsp; coinage problem tracks back to a 2002 paper what&nbsp;&nbsp;
[07:23] the country needs now is an 18 cents piece&nbsp; however i first came across it when my friend&nbsp;&nbsp; adam townsend a mathematician at durham university&nbsp; wrote an article for chalk dust and at the time&nbsp;&nbsp;
[07:36] adam was able to work out the optimal solutions&nbsp; across all possible combinations of coin values&nbsp;&nbsp; for the uk for everything up to the case for five&nbsp; coins so we now know if we only had two coins we'd&nbsp;&nbsp;
[07:49] have a 1 p and a 22p and your change on average&nbsp; would have well over 20 coins in it three coins&nbsp;&nbsp; gets us under 10 with a 1 p a 14p and a 61p and at&nbsp; the time eight years ago the computation fizzled&nbsp;&nbsp;
[08:04] out after five when i contacted adam saying i was&nbsp; finally making a video about this maybe we should&nbsp;&nbsp; dust off the code and give it another go straight&nbsp; away he got the case for six coins which was very&nbsp;&nbsp;
[08:17] exciting not long after that we got seven and then&nbsp; it seemed like we were not going to get eight the&nbsp;&nbsp; code was going to take so long to run it was hard&nbsp; to justify that amount of processing power until&nbsp;&nbsp;
[08:29] one day adam was struck with inspiration changed&nbsp; the code made it more efficient and now we have an&nbsp;&nbsp; answer which is why i'm filming this bit after all&nbsp; the other stuff you've just seen cuz it literally&nbsp;&nbsp;
[08:41] just happened and i can now present the official&nbsp; 8 coin solution if we swapped the eight current&nbsp;&nbsp; coins used in the uk for these and come on we&nbsp; get a11 coin we would have way fewer coins in&nbsp;&nbsp;
[08:57] our change would bring the average all the way&nbsp; down to 3.82 so good and i was so excited you&nbsp;&nbsp; better believe i 3d printed them so there's a uh&nbsp; 1.58 coin we got the pound 55 if you're thinking&nbsp;&nbsp;
[09:12] these are just way too big it's because i wanted&nbsp; the volume of these to be proportionate to their&nbsp;&nbsp; value so if you go all the way down to the the&nbsp; 1p that's got one 158th the mass of the pound 58&nbsp;&nbsp;
[09:28] coin so what it means is if you get your change&nbsp; and you just chuck all the coins on some scales&nbsp;&nbsp; and weigh them it'll give you the exact value&nbsp; how good are these available now or the most&nbsp;&nbsp;
[09:40] optimal set of eight coins possible and all of&nbsp; these could be yours if you just convince the&nbsp;&nbsp; government to change to these and then do a lot of&nbsp; complex arithmetic anytime you want to make change&nbsp;&nbsp;
[09:52] or because of the scaling volume just weigh your&nbsp; change and get the exact value straight away it's&nbsp;&nbsp; so dumb now you might be thinking if we found&nbsp; these coins via an exhaustive search is there&nbsp;&nbsp;
[10:06] a hey speaking of money it's time for me business&nbsp; matt get out of here so these fantastic coins we&nbsp;&nbsp; have printed for the video were all printed on&nbsp; that bamboo labs x1 printer behind me and they&nbsp;&nbsp;
[10:21] are sponsoring this video which is why i'm going&nbsp; to say it's a printer so good you can literally&nbsp;&nbsp; print money like actual money i don't think we&nbsp; can legally say they can print money look who is&nbsp;&nbsp;
[10:34] the business finance expert here you are correct&nbsp; i'm the one wearing a jacket that's how you know&nbsp;&nbsp; i'm business matt get out of here how it works&nbsp; bamboo printers so good you can literally print&nbsp;&nbsp;
[10:46] money legality to be questioned the bamboo labs&nbsp; x1c is a high-speed high quality 3d printer it&nbsp;&nbsp; can take multiple colors at once and it's got all&nbsp; sorts of smart features which actually work and&nbsp;&nbsp;
[11:05] it means even i a 3d printing novice can print&nbsp; all sorts of fantastic multicolored things and&nbsp;&nbsp; thanks to everyone who sent in models after the&nbsp; last promo we did for bamboo including andreas&nbsp;&nbsp; müller who sent this i said if enough people&nbsp; used the link and we got to do another promo&nbsp;&nbsp;
[11:22] i'd print out files people sent in so andrea&nbsp; sent in this it's a ring of regular deahedra&nbsp;&nbsp; so in theory this could be like will this go&nbsp; around my head it won't go around my head but&nbsp;&nbsp; andreas has put this model and other longer more&nbsp; flexible ones that will go around your head here&nbsp;&nbsp;
[11:38] on maker world the bamboo labs website where you&nbsp; can download all sorts of great models and thank&nbsp;&nbsp; you to adam adam lutter who sent in some assembly&nbsp; required this is what's called an industrial dice&nbsp;&nbsp;
[11:51] it's based off a design that james prop came up&nbsp; with i need to go home glue this together then i&nbsp;&nbsp; can roll it and i'll have a link below you can&nbsp; check out the mass of that so do check out the&nbsp;&nbsp; link in the description below and if enough of&nbsp; you click it we'll do another one of these send&nbsp;&nbsp;
[12:06] me in more ridiculous models and i'll print them&nbsp; out business matt away is he gone okay fuel skye&nbsp;&nbsp; we're safe come on up here good girl sit lie&nbsp; down there you go now if you're thinking if&nbsp;&nbsp;
[12:22] we found those coin combinations via exhaustive&nbsp; search surely there's a more clever way of doing&nbsp;&nbsp; it and actually when the results came in for the&nbsp; six coin setup i thought you know what that 140&nbsp;&nbsp;
[12:37] and that 99p are awfully suspicious of course as&nbsp; these numbers were coming in we were looking for&nbsp;&nbsp; patterns so we could just generate them instead&nbsp; of having to do such tedious exhaustive searches&nbsp;&nbsp;
[12:51] and at the point when we got to six so i hadn't&nbsp; seen seven or eight yet i was like "wait a minute&nbsp;&nbsp; 99 p 140." well a pound 40 that's almost the&nbsp; square root of two well 100 times it wait 99&nbsp;&nbsp;
[13:05] p that's about 100 hang on a minute it turns out a&nbsp; pound 40 divided by 99 p is &lt;unk&gt;2 how interesting&nbsp;&nbsp; but are there other ratios between the coins&nbsp; we were finding which was root two well we can&nbsp;&nbsp;
[13:20] spread this out a little bit to give us a bit more&nbsp; room and of course i calculated the ratio between&nbsp;&nbsp; every two consecutive coins for all the solutions&nbsp; we found and there's our root two and there's kind&nbsp;&nbsp;
[13:32] of root two is that root two what about this one&nbsp; that's route twoish now i believe these are close&nbsp;&nbsp; enough to indicate something is going on now we&nbsp; don't actually know what if you come up with a way&nbsp;&nbsp;
[13:45] to generate these that would be as far as i know&nbsp; all new maths and it seems like it's got something&nbsp;&nbsp; to do with square roots you could argue i'm just&nbsp; reading tea leaves here and i'm overfitting to&nbsp;&nbsp;
[13:57] what i'm seeing and there is a line so the one&nbsp; here 1.597 that's pretty much exactly the fourth&nbsp;&nbsp; root of 6.5 but i feel like that's an accident&nbsp; the route twos however that might be something&nbsp;&nbsp;
[14:11] and the reason i think it could be an indication&nbsp; what's going on is square roots do abound and if&nbsp;&nbsp; we have a closer look at the two coin case so&nbsp; you get a 1 p coin and some other coin why 22&nbsp;&nbsp;
[14:24] or 23 why are they equally good well in our case&nbsp; we have to make change up to £500 and the square&nbsp;&nbsp; root of 500 is suspiciously right between the two&nbsp; equivalent values it seems like square roots have&nbsp;&nbsp;
[14:40] a lot to do with this and the two coin case is&nbsp; the nice simple starting case we can actually&nbsp;&nbsp; investigate so let's say we have two coins one&nbsp; is worth a single pence because we need penny&nbsp;&nbsp; accuracy and then we have some other coin of some&nbsp; other value and we have to make change for any&nbsp;&nbsp;
[14:55] value from one up to some value capital n well&nbsp; i mentioned this to adam he had to think about&nbsp;&nbsp; it and he ran his code again and put together this&nbsp; plot and the blue is what came out of his code and&nbsp;&nbsp; the orange is when you fit an equation to it and&nbsp; it looks like the equation of the expected number&nbsp;&nbsp;
[15:12] of coins for when you add in some x pence coin and&nbsp; your capital n's 500 is a half 500 /x + x but why&nbsp;&nbsp; and it turns out that's true and here's why if you&nbsp; think it through the number of coins you need for&nbsp;&nbsp;
[15:29] some value little n so that's some value between&nbsp; one and capital n for one specific case you're&nbsp;&nbsp; making change you go okay well i want to use as&nbsp; many x pence coins as i can because they're the&nbsp;&nbsp; bigger value coin so you take the target n divide&nbsp; it by x that's way you got to round it down that's&nbsp;&nbsp;
[15:45] how many x pence coins you can use and the rest of&nbsp; it whatever the remainder is we can calculate the&nbsp;&nbsp; remainder that's how many 1 pence coins we need so&nbsp; that's the total number of coins for any specific&nbsp;&nbsp;
[15:57] value little n if we want to do all the values to&nbsp; capital n well we just take one n and then we sum&nbsp;&nbsp; it up for all the n's divide by n and that gives&nbsp; you the average number of coins for some coin x&nbsp;&nbsp;
[16:12] here's where we can have some maths fun and then&nbsp; by the way this is all too fast for you to follow&nbsp;&nbsp; in close detail you can pause it and have a good&nbsp; think and work it through yourself if you want but&nbsp;&nbsp; broadbrush you convert that to an integral because&nbsp; we can actually work that out exactly you do that&nbsp;&nbsp;
[16:27] integration and the equation for the number of&nbsp; coins on average for a coin x is this look how&nbsp;&nbsp; neat that is and if we want the minimum what's&nbsp; the best x well we just differentiate that set&nbsp;&nbsp;
[16:41] it to zero and would you believe it it gives you&nbsp; x= the square root of n that's where the square&nbsp;&nbsp; root comes from at least in the two coin case very&nbsp; sadly we can't extend this to three or more coins&nbsp;&nbsp;
[16:56] because of an assumption see here where we had the&nbsp; number divided by x we're basically saying do the&nbsp;&nbsp; biggest coin first do as many as you can then&nbsp; do the next coin down and that while it seems&nbsp;&nbsp; intuitive and logical that's called the greedy&nbsp; algorithm and very sadly it doesn't always hold&nbsp;&nbsp;
[17:14] the greedy algorithm is where you take the next&nbsp; biggest coin to get up to the total you're aiming&nbsp;&nbsp; for and i hate to admit it but it means that these&nbsp; are not very practical because in over half the&nbsp;&nbsp;
[17:26] cases 320 out of 499 change scenarios the greedy&nbsp; algorithm doesn't work so if you had to make&nbsp;&nbsp; change for 31 p you'd be like well we got to use&nbsp; the 28 first cuz that's the biggest one under 31&nbsp;&nbsp;
[17:42] and then we make it up with three pennies and that&nbsp; would be four coins because you went biggest first&nbsp;&nbsp; however if you skipped over the biggest one and&nbsp; instead you picked up the 21p you then only need&nbsp;&nbsp;
[17:55] two 5ps to make up the total that's only three&nbsp; coins and our normal coinage doesn't have this&nbsp;&nbsp; problem this better coinage does and the worst&nbsp; case scenario by the way is if you had to make two&nbsp;&nbsp;
[18:09] coin's the 158 we'll do that we then need uh two&nbsp; 28s we need two fives and then we can make up the&nbsp;&nbsp; rest with four ones which is a lot of coins and&nbsp; you've completely neglected to notice that 228 is&nbsp;&nbsp;
[18:28] just the 155 and the 73 you can do it in two coins&nbsp; that's seven fewer it's just super not obvious&nbsp;&nbsp; so not only are these coins unusual numbers that&nbsp; make the arithmetic difficult but you can't even&nbsp;&nbsp;
[18:44] do it the normal easiest way you got to use&nbsp; difficult numbers and do it the hard way so&nbsp;&nbsp; there you are opportunity for way more maths&nbsp; in my mind however now i return you to past&nbsp;&nbsp;
[18:56] matt he's probably banging on about what's more&nbsp; practical there is another solution to simplify&nbsp;&nbsp; change that we're overlooking here and it is&nbsp; dare i say a practical which i appreciate is the&nbsp;&nbsp;
[19:09] thinking there's no way i'm using those coins and&nbsp; there's no way the general public are going to be&nbsp;&nbsp; adding up ridiculous coin denominations well it's&nbsp; simple we keep all the values we currently have&nbsp;&nbsp;
[19:24] and to simplify it we just get rid of the one&nbsp; and two pence coins and just by getting rid of&nbsp;&nbsp; them and rounding our change to the nearest 5 p we&nbsp; will drop the average number of coins all the way&nbsp;&nbsp;
[19:39] down to 3.4 way better and if you think well hang&nbsp; on people aren't going to do that people won't be&nbsp;&nbsp; happy rounding their change well in australia they&nbsp; got rid of the one and two cent coins they had an&nbsp;&nbsp;
[19:53] identical range to what we have in the uk got&nbsp; rid of one and two cent coins in the early '9s&nbsp;&nbsp; and for over a third of a century it's worked&nbsp; fine for more on this we go to on location
[20:07] matt thank you studio matt no you hang up are&nbsp; we not doing that i thought we were anyway i'm&nbsp;&nbsp; here on location in australia and i can confirm&nbsp; and i remember this in the '9s we got rid of the&nbsp;&nbsp;
[20:23] one and two cent coins and nobody cared no one&nbsp; cares now we still have the notion of 1 cent&nbsp;&nbsp; because if you pay electronically or you know&nbsp; with a card you pay to the nearest whole cent&nbsp;&nbsp;
[20:35] if you pay cash rounded to the nearest 5 cents&nbsp; so actually if you're a little bit strategic and&nbsp;&nbsp; you choose between cash or card depending on&nbsp; which way the rounding is going to go you can&nbsp;&nbsp; save literally ones of cents in a lifetime but&nbsp; what about selfch checkckout machines well of&nbsp;&nbsp;
[20:51] course there is a supermarket here at the beach&nbsp; that has selfch checkouts and i've worked out if&nbsp;&nbsp; i go in there and spend these 10 dollars and the&nbsp; machine has to give me $3.85 85 cents change it&nbsp;&nbsp;
[21:06] should do it with one of all six different&nbsp; coins available if it has them let's find out as is tradition once i got to the supermarket&nbsp; i went to the stationary aisle this time i found&nbsp;&nbsp;
[21:21] a clear plastic ruler 30 cm for $25 i just have&nbsp; to add to that a single box of barbecue shapes&nbsp;&nbsp; for four wait a minute two halfp price boxes&nbsp; of barbecue shapes for $4 bonsai and that's&nbsp;&nbsp;
[21:37] going to give me exactly $385 change put in my&nbsp; 10 bucks and here comes the change there's a&nbsp;&nbsp; $2 coin or $1 coin and following that what a heap&nbsp; of 20 cent coins where's my 50 cent where's the&nbsp;&nbsp;
[21:54] 10 unbelievable coals have given me three 20 cent&nbsp; coins three coins when i should have had a 50 and&nbsp;&nbsp; a 10 that's one more coin overall than was optimal&nbsp; what on earth is going on with selfch checkckout&nbsp;&nbsp;
[22:07] machines i'll tell you what i'm going to email&nbsp; coohl's and if they reply i'll edit their response&nbsp;&nbsp; in right now nothing nothing i guess they didn't&nbsp; get back to me the point is whatever's happening&nbsp;&nbsp;
[22:20] with these soft checkout machines just doesn't&nbsp; measure up but that's it from me here in australia&nbsp;&nbsp; no longer have one and two cent coins although&nbsp; interestingly never replace them with anything&nbsp;&nbsp;
[22:32] else h back to you studio matt thank you on&nbsp; location matt no you hang up oh we're not doing&nbsp;&nbsp; that bit oh sorry anyway so if we get rid of the&nbsp; one and two pence coins and we replace them with&nbsp;&nbsp;
[22:48] two new coins which australia didn't do we can do&nbsp; even better and now we don't get any weird values&nbsp;&nbsp; because everything is a multiple of five and for&nbsp; some reason everyone's okay with that so if we get&nbsp;&nbsp;
[23:00] rid of one and two and replace them with 165 and&nbsp; 225 we bring the average number of coins in change&nbsp;&nbsp; in the uk down to 2.6 under three how good is&nbsp; that and if you want to take this opportunity to&nbsp;&nbsp;
[23:17] simplify the whole system and not have eight coins&nbsp; we could go down to just seven coins by replacing&nbsp;&nbsp; one and two pence with a single 1.75 coin which&nbsp; is quite nice and actually adam had an idea for&nbsp;&nbsp;
[23:34] the design of that coin when adam presented&nbsp; his initial findings at the mass jam weekend&nbsp;&nbsp; many years ago he showed the original design&nbsp; for the current coins which has this fantastic&nbsp;&nbsp; shield pattern you can see all of it on the one&nbsp; pound coin and then fragments on it of the six&nbsp;&nbsp;
[23:51] other coins of lesser value now since then the one&nbsp; pound coin has been updated to a different design&nbsp;&nbsp; but we still have the shield on the other coins&nbsp; it's a wonderful little thing that often people&nbsp;&nbsp;
[24:03] don't notice and when they do it's a fun easter&nbsp; egg but adam realized if we took out the one and&nbsp;&nbsp; two pence coins we even further lose the shield&nbsp; so if we're going to replace that with a 175&nbsp;&nbsp;
[24:15] coin it needs to fill those two gaps at the same&nbsp; time and this is what adam designed and presented&nbsp;&nbsp; with a sufficiently straight face in front of a&nbsp; room of other recreational mathematicians and i&nbsp;&nbsp;
[24:29] thought this design was so great i asked adam for&nbsp; his slides which is why i'm showing them to you&nbsp;&nbsp; now i think it's some of his best artistic work&nbsp; if i'm being honest i mean look at that look at&nbsp;&nbsp; that double one 75 coin the lion is roaring that's&nbsp; excellent but you know no one's going to actually&nbsp;&nbsp;
[24:47] try and make it you know i printed it there it&nbsp; is i managed to recreate adam's incredible design&nbsp;&nbsp; i mean you could just see the shield now this&nbsp; is a 2:1 scale because i tried to print it the&nbsp;&nbsp;
[25:02] exact right size and my 3d modeling abilities are&nbsp; not good enough yet but that's still a proof of&nbsp;&nbsp; concept that's a prototype now that's a practical&nbsp; coin i'll be honest my vote is just dump the one&nbsp;&nbsp;
[25:15] and two pence coins don't replace them simplify&nbsp; it down to a mere five coins so tidy and other&nbsp;&nbsp; countries have got a much smaller set of coins for&nbsp; example the currently united states of america and&nbsp;&nbsp;
[25:32] we have sadly on location matt couldn't make it&nbsp; but we do have a us correspondent for the channel&nbsp;&nbsp; rolling hey how's it going i'm raleigh williams&nbsp; i'm here in the united states of america i'm from&nbsp;&nbsp;
[25:44] the youtube channel climate town check it out&nbsp; on youtube.com in america we have six coins but&nbsp;&nbsp; if you think we're using all of them you're out&nbsp; of your goddamn mind we only have four in normal&nbsp;&nbsp; circulation two of them we never use including the&nbsp; half dollar and the honken dollar coin this thing&nbsp;&nbsp;
[26:01] weighs as much as a house we just have it to show&nbsp; that we're better than everybody so that's how&nbsp;&nbsp; we do it in america and as far as i'm concerned&nbsp; that's how everyone should do it all around the&nbsp;&nbsp; world usa usa usa catch the fever indeed usa&nbsp; and that actually answers our question about&nbsp;&nbsp;
[26:23] sainsburries because if you have a close look&nbsp; at the sainsbur selfch checkout that i was using&nbsp;&nbsp; it's an ncr model plus you might have noticed the&nbsp; machine in australia also ncr and the company ncr&nbsp;&nbsp;
[26:36] that makes them is an american company the selfch&nbsp; checkckout machines are designed for american&nbsp;&nbsp; coinage or at least designed for countries with&nbsp; fewer coins i don't know why it's six maybe it's&nbsp;&nbsp;
[26:48] the five normal ones and then they've got the&nbsp; $1 coin as an option but they're definitely not&nbsp;&nbsp; designed for eight coins so sainsburries they're&nbsp; not going to pay for a whole new type of machine&nbsp;&nbsp;
[27:00] the uk market is obviously not big enough for&nbsp; that so what they've done is just gotten rid of&nbsp;&nbsp; two of the coins they took out 50p and 10p but&nbsp; are those the best two coins to take out i had&nbsp;&nbsp;
[27:13] a look into it do you want to see do you want to&nbsp; see a plot of course you want to see a plot i've&nbsp;&nbsp; got a table here of every pair of coins that could&nbsp; be removed i've only filled in the ones where like&nbsp;&nbsp;
[27:26] it's a unique pairing of coins and green is good&nbsp; red is bad and the best one here is if you take&nbsp;&nbsp; out the pound coin the 100 and you take out the&nbsp; 10p coin so instead of doing 10 and 50 they should&nbsp;&nbsp;
[27:39] have done 10 and 100 because that would give you&nbsp; an average of 5.41 coins in your change but they&nbsp;&nbsp; didn't do that they didn't do any of these all&nbsp; of these are better in fact if they took out&nbsp;&nbsp; the pound and any of the 2p 5p 10p and 20p it'd&nbsp; be better than what they've currently got now&nbsp;&nbsp;
[27:56] maybe they felt people wouldn't tolerate there&nbsp; not being a one pound coin if they didn't take&nbsp;&nbsp; that out but that's the optimal solution or they&nbsp; could have taken out the two pound coin and the&nbsp;&nbsp; 10p coin or they could have taken out the 10p coin&nbsp; and the 2p coin all of those are better instead&nbsp;&nbsp;
[28:16] they took out the 50p and the 10p which is now&nbsp; like what the seventh best option and i have no&nbsp;&nbsp; idea why they did that when there are way better&nbsp; options actually you know what i might i might&nbsp;&nbsp;
[28:31] email them i didn't think to ask i just worked&nbsp; this out to be honest you know what i'm going to&nbsp;&nbsp; send them an email and if they give me a sensible&nbsp; explanation i will put it in the edit right here
[28:45] nothing i guess i didn't reply honestly sainsbur&nbsp; springs so in conclusion i don't know money is&nbsp;&nbsp; terrible i mean not coins coin i mean money&nbsp; is made up but uh coins are terrible i mean&nbsp;&nbsp;
[29:00] i haven't used physical money in a very long&nbsp; time and that's the first time i've gotten&nbsp;&nbsp; change from a selfch checkckout machine in i&nbsp; would say about a decade because we don't we&nbsp;&nbsp; don't need physical money uh anymore and that's&nbsp; why i'm very pleased to announce matt coin when&nbsp;&nbsp;
[29:16] i know wouldn't that be special if that's what&nbsp; i was doing no uh hey thanks for watching thanks&nbsp;&nbsp; for supporting the channel uh by the way i don't&nbsp; need another one of these in my life so if you&nbsp;&nbsp;
[29:28] would like this or indeed the coins i will uh&nbsp; sign the coins i'll sign this they're all on&nbsp;&nbsp; ebay you can pay electronically or post me might&nbsp; no you can't post me money uh all the money goes&nbsp;&nbsp; to charity for these thank you to everyone on&nbsp; patreon who gives me uh real digital money to&nbsp;&nbsp;
[29:45] keep the channel ticking along uh a huge thanks&nbsp; to adam townsen for doing the maths inspiring&nbsp;&nbsp; this video helping me put it together and of&nbsp; course thanks to jeffrey shallot who did the&nbsp;&nbsp; original what this country needs now is an 18&nbsp; cent piece i'll link to all of it below thank&nbsp;&nbsp;
[30:00] you for watching um bye be the change you want to&nbsp; see in the world that's what i should have said
[30:12] world h this is not a serious career