Dominoes spots from one to six are generally arranged as they are on six-sided dice, but because blank ends having no spots are used, seven faces are possible, allowing 28 unique pieces in a double-six set. However, this is a relatively small number especially when playing with more than four people, so many domino sets are "extended" by introducing ends with greater numbers of spots, which increases the number of unique combinations of ends and thus of pieces. Each progressively larger set increases the maximum number of pips on an end by three, so the common extended sets are double-nine, double-12,
Dominoes being able to be removed without damage. The phenomenon also has some theoretical relevance (amplifier, digital signal, information processing), and this amounts to the theoretical possibility of building domino computers. Dominoes are also commonly used as components in Rube Goldberg machines. The Netherlands has hosted an annual domino-toppling exhibition called Domino Day since 1986. The event held on 18 November 2005 knocked over 4 million dominoes by a team from Weijers Domino Productions. On Domino Day 2008 (14 November 2008), the Weijers Domino Productions team attempted to set 10 records: This record attempt was held in the in Leeuwarden. The