Quarter farthing Quarter farthing The British quarter farthing (d) coin was a unit of currency equaling one sixteenth of a penny ( of a pound sterling). It was produced for circulation in Ceylon in various years between 1839 and 1853, with proof coins being produced in 1868. It is the smallest denomination of pound sterling coin ever minted. The coin is considered to be part of British coinage because it has no indication of what country it was minted for, being made in the same style as the contemporary half-farthing which was legal tender in Britain between 1842 and 1869. Before Decimal
Penny graph Penny graph In geometric graph theory, a penny graph is a contact graph of unit circles. That is, it is an undirected graph whose vertices can be represented by unit circles, with no two of these circles crossing each other, and with two adjacent vertices if and only if they are represented by tangent circles. More simply, they are the graphs formed by arranging pennies in a non-overlapping way on a flat surface, making a vertex for each penny, and making an edge for each two pennies that touch. Penny graphs have also been called unit coin graphs, because they