The terms "pound," "shilling," and "penny" refer to units of currency that were used in the United Kingdom before the decimalization of the currency in 1971. The pound (£) was the main unit, while the shilling (s) was worth one-twentieth of a pound, and the penny (d) was worth one-twelfth of a shilling. This system created a complex relationship between the three units, with 240 pennies making up a pound. Before decimalization, the currency system was based on a system of 12 and 20, which made calculations more complicated. For example, there were 20 shillings in a pound and 12 pennies in a shilling. The introduction of the decimal system simplified currency, making it easier to understand and use, with 100 new pence now equaling one pound.