Twenty pence (British coin) Gardner, and used from 1982 to 2008, is a crowned Tudor rose, with the numeral "20" below the rose, and above the rose. To date, three different obverses have been used. On coins minted before the 2008 redesign, the inscription is . Coins minted after the 2008 redesign also have the year of minting on the obverse. Like all the new decimal coins introduced in 1971, until 1984 the portrait of Queen Elizabeth II by Arnold Machin appeared on the obverse, in which the Queen wears the 'Girls of Great Britain and Ireland' Tiara. Between 1985 and 1997 the portrait
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