Dadu ni kidude ambacho kwa kawaida kina umbo la mchemraba lakini kuna aina nyingine pia. Inatumiwa kwa kuirusha katika michezo ya bahati au pia katika mchezo ambako namba inahitajika kwa njia ya kubahatika. Dadu ya kawaida huwa na pande sita na namba kwenye ya kila upande. Kwa kawaida namaba hizi ni 1, 2, 3, 4, 5 na 6. Jumla ya namba za pande mbili za kinyume huwa ni 7. Dadu inarushwa kwenye sehemu tambarare ama mezani au kwenye sakafu ya chumba. Namba au alama inayofika juu ni ya kubahatika. Kurushwa kwa dadu kunatokea ama kwa mkono au baada ya kutikisisha ndani ya chombo. Wikimedia Commons ina media kuhusu: Dadu "Fair Dice" is an illustrated Math Games column about all the possible fair dice, and the mathematical reasons why other shapes are not fair. A complete list of all possible Fair Dice which has nice illustrations Animation clearly demonstrating the probability space of dice World's Largest Dice Collection Links, Photos, Information about dice Computer Simulation of Irregular Dice Archived 7 Agosti 2011 at the Wayback Machine. "A Pair of Dice Which Never Roll 7" The oldest backgammon set found in Iran Archived 5 Aprili 2012 at the Wayback Machine.