Decimal Day is the name that was given to 15 February 1971 in the United Kingdom (UK). It was the day that the UK decimalised (converted to a decimal-based system of currency). Before that date the UK used the "pound (£) - shilling (s) - pence (d)" currency system. The old system was known as the "£sd" system, after the abbreviations of the unit names. £sd is pronounced L-S-D. In the £sd system £1 = 20s and 1s = 12d, so £1 = 240d. In the new decimal system there are no shillings and there are 100 (new) pence (abbreviated as "p") in a pound - so £1 = 100p.[1]
References
.svg){kind=small}