£.s.d.
Until UK currency changed in 1971, when the pound (£) became equivalent to 100 pence (called ‘decimalisation’), people certainly knew their multiples and factors of 12, as well as 20, very well indeed. Everyone had the following mathematical facts at their fingertips:-
| UNIT | SYMBOL | EQUAL TO |
| pound | £ | 20 shillings |
| shilling or ‘bob’ | s. or /- | 12 pennies |
| penny | d. | 2 halfpennies |
| halfpenny | d. | 2 farthings |
| guinea | gn. | one pound and one shilling, or 21/- |
| florin or ‘two bob’ | 2/- or 2s. | 2 shillings |
| half crown or ‘dollar’ | 2/6d. or 2/6 | 2 shillings and sixpence, or 30d. |
In addition to these, there were the 12-sided threepence (3d.), or ‘thrupenny bit’, and the silver sixpence (6d.), also known as a ‘tanner’. A farthing was quarter of a penny and went out of circulation in 1960. The halfpenny (pronounced hape-nee) went out in 1969 and the half crown in 1970, as did the 10 shilling (10/-) note. The shilling coins were used as 5p coins until 1990 and the florins were used as 10p coins until 1993. The little silver sixpences were worth 2.5p, so only survived until 1980.
(Image: Adrian Clark on Flickr.com / CC BY-ND 2.0)