Our crazy old currency, complete with farthings, ha’ppennies, pennies, tuppences, thre’penny bits, tanners, shillings or bobs, two-bobs, half-a-crown, crown, pound, and guinea was generally known as ‘the duodecimal system’ ~ but only once we had started discussing then implementing the alternative…
¼ penny = farthing (obsolete from waybackwhen)
½ penny = “ha’pence” or “ha’penny”
1 penny = 1d
2 pennies = “tuppence” or “tuppeny piece”
3 pennies = “thre’penny bit” or “thre’pence”
6 pennies = “sixpence” or “tanner”
12 pence = 1 shilling (1/-) ~ also known as “a bob”
24 pence = 2 shillings (2/-) ~ in single coin, known as “two-bob”
30 pence = 2 Shillings 6 pence (2/6) ~ also known as “two-and-six” or “half a crown”
60 pence = 5 shillings = crown (rarely in circulation)
120 pence = 10 shillings (10/-) ~ also known as “ten-bob note”
240 pence = 20 shillings (20/-)* = 1 pound (£1/-/-)* ~ also know as “a quid”
252 pence = 21 shillings = 1 guinea (ancient terminology beloved of lawyers)
*I can’t actually remember this notation accurately.
Can you see why it was so indigestible? And speaking of which:
Duodenum
[med.L. (so called from its length, = duodénum digitorum space of twelve digits, inches, or finger's breadths), f. duodéni twelve each (see duodene). Used in Fr. in 1514 (Hatz.-Darm.).]© OED v2