Decimal Day remain valid back to 1971, the only circulating coins valid on Decimal Day still to be valid. In 1982, the word "new" in "new penny" or "new pence" was removed from the inscriptions on coins, to be replaced by the number of pence in the denomination (i.e. "ten pence" or "fifty pence"). This coincided with the introduction of a new 20p coin, which, from the outset, simply bore the legend "twenty pence". A £1 coin was introduced in 1983, and a £2 coin in 1997. When the old pounds, shillings, and pence system was in operation, the United Kingdom and
Cocker's Decimal Arithmetick Cocker's Decimal Arithmetick Cocker's Decimal Arithmetick is a grammar school mathematics textbook written by Edward Cocker (1631–1676) and published posthumously by John Hawkins in 1684. "Decimal Arithmetick" along with companion volume, "Cocker's Arithmetick" published in 1677, were used in schools in the United Kingdom for more than 150 years. The concept of decimal fractions and the advantages of using them in calculations were well known, but a wide variety of different notations were in use. After surveying various notations, "Decimal Arithmetick" recommends the decimal point notation introduced by John Napier: "Decimal Arithmetick" gives instructions for calculations involving decimals, methods of