This question quotes Terry Pratchett's claim:

The British resisted decimalized currency for a long time because they thought it was too complicated.

Is this a fair comparison with its inference that British currency was significantly more complex than decimal currency?

Or is it a simple matter of lack of familiarity leading to misunderstanding?

For purposes of comparison, even though it is a century earlier, the era of interest I believe is best taken from 1800 to 1850, early to mid 19th century. Both the U.K. and U.S. are then on a metallic currency standard, and the smaller coins in both currencies still retain real buying power. I believe this provides a better comparison than latter time periods, say after the Second World War, would.


Although I have posted an answer below, I have no intent to accept it. The material there is posted as a resource for any and all who would care to attempt a definitive answer.


  • Comments are not for extended discussion; this conversation has been moved to chat.
    – MCW
    Commented Feb 2, 2021 at 15:04
  • For a good overview of British currency pre-decimalisation see youtu.be/R2paSGQRwvo It turns out to be surprisingly rational.
    – DrMcCleod
    Commented Feb 3, 2021 at 18:24
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    One of the big drivers for decimalisation was the use of computers for accounting. Big companies needed to computerise to compete, but they couldn't buy off-the-shelf computers and accounting programs that worked for the rest of the world because of our weird currency. At one point ICL produced machines which had special hardware for sums with UK money, but IBM weren't going to do that. International trade was similarly complicated. Hence a drive to switch to something that the rest of the world understood. Commented Feb 4, 2021 at 14:46
  • 1
    @MarkJohnson: Don't be absurd. Every single large corporation was flooding the postal systems with "Do not fold, spindle or mutilate" 80-column punched cards to be returned with bill payments, etc. No household with a mortgage or utility bill was unaware of the computers being used to tabulate and print those bills, and process the return payments. My high school purchased its first small computer in 1971. H.P. and T.I. Electronic calculators were ubiquitous by 1974, to the extent that exams no longer accommodated slide-rule equipped students by 1975. Commented Feb 4, 2021 at 20:24
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    @MarkJohnson: Here is the HP Christmas Guide featuring the HP-55 at MSRP of USD $355. For my Circuits II exam in spring 1976 I was the only student without a calculator, and the Professor opted to not make all triangles Pythagorean - making the exam a VERY VERY long one for me doing it on a slide rule. Other calculators were available at lower prices: HP-25 was just MSRP $195 for xample. Commented Feb 4, 2021 at 20:47

7 Answers 7


[Another] question quotes Terry Prattchett as:

"The British resisted decimalized currency for a long time because they thought it was too complicated."

Is this a fair comparison with its inference that British currency was significantly more complex than decimal currency?

No. The quote is from Good Omens, by Terry Pratchett (not Prattchett) and Neil Gaiman. It's a humorous work and the quote is an ironic joke, not a factual claim. Of course the process of changing over was complex even though the new system was simpler. (Wikipedia seems very prim, with its continual mentions of Decimal Day. In practice, it was known as D-Day, to cash in on the historical allusion to WWII.)

I'm old enough to have used both systems. Whilst the pre-decimalisation system was objectively more complex with its base 12 and base 20 calculations than an all base 10 system, using £sd coins was no harder for day-to-day transactions for those familiar with it than using decimal coinage. More involved activities, such as working out interest rates, were complicated by having to work in multiple bases but for everyday work this was offset by the extra factors available working in base 12 rather than base 10. (⅓ of 2/- -> 8d. ⅓ of 10p -> oops.) Plus we kept up our mental arithmetic skills by not having calculators.

  • 5
    Working with pre-decimal currency may have been easy for people who grew up using it, but I'd bet it was fairly baffling to tourists and immigrants... Commented Feb 2, 2021 at 10:13
  • 9
    When in foreign climes, I tend to proffer my wallet to the vendor, who then proceeds to select a few notes and return me a few coins. Works every time.
    – Mawg
    Commented Feb 2, 2021 at 10:29
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    @user3153372 "baffling to tourists" is an interesting point; the British Lsd system is famously adapted from the Latin "librae, solidi, and denarii", though the ancient Roman system was actually rather different and I think the English Lsd came from the Franks. At one stage similar divisions were widespread throughout Europe: 1 livre = 20 sols/sous = 240 deniers in pre-revolutionary France, for example, but with national variations, e.g. Dutch 1 gulden = 20 stuivers = 160 duit = 320 penningen, Ottoman 1 kuruş = 40 para = 120 akçe. See e.g. en.wikipedia.org/wiki/Non-decimal_currency
    – Silverfish
    Commented Feb 2, 2021 at 20:27
  • 11
    @chepner that's a very US-centric view. In Britain unlike the US, for a time we kept up quite well with the pace of converting notes to coins when inflation justified it. So where your largest coin in common usage (ignoring the dollar and half dollar which are rarer) is worth 18p, our largest coin in common usage is worth £2. As you can imagine lots more people in Britain will pay for things with coins. (Though of course with the advent of contactless cards and COVID lots of people are now using coins and cash less).
    – Muzer
    Commented Feb 3, 2021 at 0:08
  • 4
    @OscarBravo Unless it was a fancy car; then it would have been 534 guinea.
    – user13415
    Commented Feb 3, 2021 at 12:42

Here is a comparison chart with rough equivalences between coin values. I've matched coins at an approximate ratio of "1£ : $4" as covering both coin ranges and approximating the exchange rate of the time.

s. / d.1 Pence Equiv. Coin / Note Name U.S. Value Cents Equiv. U.S. Coin
0 / ⅛ ⅛ d. Half-Farthing - - -
0 / ¼ ¼ d. Farthing $0, ½₵ ½₵ Half Cent
0 / ½ ½ d. Ha'penny (Half-Penny) $0, 1₵ 1₵ Cent (Penny)
0 / 1 1 d. Pence - - -
0 / 2 2 d. Tuppence (Two-Pence) $0, 5₵ 5₵ Half Dime (later Nickel)
0 / 3 3 d. Thruppence (Three-Pence) - - -
0 / 4 4 d. Fourpence (Groat) $0, 10₵ 10₵ Dime
0 / 6 6 d. Sixpence (Tanner) - - -
1 / - 12 d. Shilling or Bob $0, 25₵ 25₵ Quarter
2 / - 24 d. Florin $0, 50₵ 50₵ Half Dollar
2 / 6 30 d. Half a Crown - - -
5 / - 60 d. Crown (Five Shillings/Bob) $1, 0₵ 100₵ Dollar
10 / - 120 d. Ten Bob (Note) $2, 50₵ 250₵ Quarter Eagle
20 / - 240 d. Sovereign (£) $5, 0₵ 500₵ Half Eagle
21 / - 252 d. Guinea (Coin) - - -
- - - $10, 0₵ 1000₵ Eagle
- - - $20, 0₵ 2000₵ Double Eagle

As can be seen, both currencies covered this range of value with 12 and 11 distinct coins respectively, many with unique names, in approximately the same ratios to each other. I've always been more familiar with the decimal system, but I see neither has being inherently more or less complex than the other, given equal familiarity.


  1. Standard British abbreviation for "Shillings and Pence"
  • 14
    The abbreviations comes from: denarius 1/240 ; solidus = 12 denarii ; libra = 20 solidi Commented Feb 1, 2021 at 21:19
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    [from his biography] Baron of Mauá, the first Brazilian industrialist in the XIX c., started as a poor office boy inside an import firm. After studying math at night, he could make calculations in pounds/s/d/etc. British merchants in Rio de Janeiro often exploited their counterparts' lack of math skills or knowledge of the Imperial system to make a rounding "error" and get a few extra $. Thus, his boss was happy when he noticed that the English could not fool that boy, and promoted him.
    – Luiz
    Commented Feb 1, 2021 at 22:08
  • 5
    Amounts would be written without embedded spaces and 0d would be shown as a hyphen. So the value of a florin (a tenth of a pound) would be written as 2/-. When spoken the forward slash would be pronounced as "and". "Pence" would be omitted for amounts over a shilling, so the value of a half crown would be pronounced as "two and six".
    – Graham Nye
    Commented Feb 2, 2021 at 1:47
  • 13
    @Pieter If I pay for a £10.05 item with a £20 note and a 5p coin a young sales assistant will stare at me as if I'd grown a second head. Conversely if I paid for the same item with just the £20 note an older assistant will ask me "have you got the 5?" in order to avoid counting out a handful of change.
    – Graham Nye
    Commented Feb 2, 2021 at 15:25
  • 7
    Better. Unofficially, post-decimalization, was the Maggie (the new £1 coin in the 1980s). Because it was thick, brassy, and thought it was a sovereign. Commented Feb 2, 2021 at 17:42

My Grandmother, who was a teacher, said that adults back then naturally thought in fractions and not decimals. You've got to consider there were no pocket calculators and for both mental arthritic and abacuses divisions in terms of ratios of natural numbers. Everything someone experienced growing up in those days: Measuring devices (no digital scales then, scale weights came in fractions), clocks, coinage was in fractions. Units were in base 12, 14 or 20 because they divided nicely into more numbers, how often did you multiply or divide by 10 back then?

There was plenty of people who "didn't get" decimals, no joke. These days with pocket calculators and decimal currency children grow up dealing with decimals and now find fractions the harder of the two (look the difficulty they have with clock times) but that wasn't always the case.

  • 1
    A lot of it is just familiarity. E.g. people who grew up with the metric system probably find all those confusing prefixes (centi, milli, micro &c - all the way from yocto to yotta) to be second nature, and think that sensible US units are confusing. And vice versa, of course :-)
    – jamesqf
    Commented Feb 3, 2021 at 16:45
  • Nice! Even today the representation of many irrational numbers, such as surds, can be and often is expressed to infinite precision with a (repeating and finite) continued fraction rather than with the irregular decimal expansion. This can be a great memory saver in computere programs for example. Commented Feb 3, 2021 at 17:19
  • 1
    Shouldn't "mental arthritic" be in fact "mental arithmetic" ? Interesting lapsus lingae... Commented Feb 3, 2021 at 17:47
  • 1
    It is not all arbitrary, as the metric system is not just decimals. Think about a swimming pool of 10m x 10m x 1m. How much does the water weight? What is its the volum in liters? Easy: it has 10x10x1 m^3, that is 100m^3, that is 100.000 liters. As 1m^3 = 1 ton, the water weights 100 tons = 100.000 kg, exactly. Now, do the same with 10x10x1 but with yards, pounds, feet^3.... Another example, one liter of milk weights 1 kg, and its volume is 10x10x10 cm or 0.001 m^3. I think the universality and interchangeability of the SI units are the best about the metric system, not the decimality itself
    – Luiz
    Commented Feb 3, 2021 at 19:34
  • 2
    @Luiz: But why on Earth would I want to weigh the water in a swimming pool? And one liter of milk does not weigh 1 kg (whole milk, anyway, I can't speak to the nonfat stuff). If you ever get non-homogenized milk straight from the cow and let it sit for a bit, you'll see that the cream separates and comes to the top, because it's lighter.
    – jamesqf
    Commented Feb 4, 2021 at 4:48

I was there. (1960s) It was not confusing. Divide one old pound by three is 6/8. (six shillings and eight pence.) Divide a modern pound or a dollar by three and...

The same goes for multiplication. Three jam doughnuts at fourpence is instantly a shilling.

Having distinctive coinage made things easier still. 7/6 is three half-crowns (Instant after nearly 50 years) or if you gave a ten-bob note you'd expect one as change.

  • The similar sizes of half-crowns and florins was not helpful
    – Henry
    Commented Feb 3, 2021 at 10:12
  • 3
    I guess the question is why would you need to divide a pound by 3?
    – Tim
    Commented Feb 3, 2021 at 12:30
  • 6
    if there are three of you @Tim
    – JCRM
    Commented Feb 3, 2021 at 14:46
  • 2
    @Tim If a pound contains 240 pence then dividing it by 5 gives you 48 pence.
    – Baz
    Commented Feb 3, 2021 at 14:50
  • 2
    4 shillings or 2 florins, surely, @Baz?
    – JCRM
    Commented Feb 3, 2021 at 14:53

It wasn't in the least confusing to those of us who grew up with it. It's rather like asking how difficult do Germans find learning the German language.


Anecdote: The Viscount of Mauá (born 1813) was an early Brazilian industrialist, who had humble beginnings and no formal schooling. I read a bestseller bio about him.

One of his first jobs as an older teen, was in a importer/exporter firm in Rio de Janeiro, owned by a Scotsman. The young Irineu worked by day and studied at night by himself.

His boss realized that he could deal with sterling accounts without being bamboozled by other British merchants. This was noted by his boss as very rare - most British merchants could hide a few shillings into balances "wrongly" calculated and never double-checked by clueless Brazilians.

Because of that he got promoted. After a few years he ended up as a manager, then a partner and finally owner when his boss decided to return to Scotland.


They resisted it because they were familiar with pounds, shillings and pence amd unfamiliar with the decimal system.

Why a system designed for physics should be used for commerce and daily life is another qurstion. And the obvious answer, is there is no obvious connection and that there is no need. Besides, physics has many systems of units other than the purely decimal. For example, electron mass is routinely measured in eV.

  • and distance in meters, mass in grammes - electon-volt is just another unit nothing to do with decimals or fractions
    – mmmmmm
    Commented Sep 22, 2022 at 14:49

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