You clearly haven't worked out how many shillings there are to a pound, or to a crown for that matter, from M. Pratchett's explanation. The whole foundation of

You clearly haven't worked out how many shillings there are to a pound, or to a crown for that matter, from M. Pratchett's explanation. The whole foundation of this "10 isn't divisible by 3" and "it only has prime factors 2 and 5" argument is fundamentally flawed, undermined by the fact that (as the headlined article quite clearly pointed out) several old units used vigesimal, which also is only evenly divisible by two prime factors: 2 and 5. Indeed, reading the headlined article reveals the important point that there are eight furlongs to a mile, which is only evenly divisible by one prime factor, putting the lie even more to the "it's because they're also divisible by 3" arguments. There's a multiple of 4 in the headlined article. And other units elsewhere were subdivided into 16ths. Some were sometimes subdivided into 14ths, for reasons that this article touches upon but doesn't actually go into in enough depth: namely that standards in different places were so out of synch in Mediaeval Europe that multiplying by 16 in one town sometimes gave the same length/weight/whatever as multiplying by 14 in another town, and people formalized that to try to make things work. The idea that the pre-cursors to the metric system were some wonderfully Babylonian system composed purely of 12s and 60s is nonsense.