Halfpenny (Irish decimal coin) Halfpenny (Irish decimal coin) The decimal halfpenny (p) () coin was the smallest denomination of the Irish pound. It was first issued when the Irish currency was decimalised on Decimal Day, 15 February 1971. It was one of three new designs introduced all in bronze and featuring ornamental birds on the reverse. The coin value was weakened by inflation and very few were produced beyond the initial run for 1971. It was removed from circulation and demonetised on 1 January 1987. The main reason that halfpennies were issued was that when shillings were decimalised they were worth five new pence,
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