A Diaconis mathematician compared shuffling techniques . Dealers using a 'riffle ' shuffle need to repeat the process seven times to get a random pack of cards , said Peri Diaconis . This technique involves cutting a deck and shuffling the halves together . Whereas 'overhand ' needs to be repeated 10,000 times to get same results . The 'smooshing ' or wash method takes one minute to randomise cards .
A Stanford University mathematician compared shuffling techniques . Dealers using a 'riffle ' shuffle need to repeat the process seven times to get a random pack of cards , said Peri Diaconis . This technique involves cutting a deck and shuffling the halves together . Whereas 'overhand ' needs to be repeated 10,000 times to get same results . The 'smooshing ' or wash method takes one minute to randomise cards .