article_snippet: But a mathematician has pointed out that card aerobatics do not guarantee a random and well shuffled pack.
article_snippet: In a video for Numberphile, ’ Dr Diaconis compared shuffling styles to explain styles efficiency (illustrated)
article_snippet: SIMPLE METHOD looks random and is – if It is done for a long enough period time.
article_snippet: Dr Diaconis explained in the video how mathematicians check that shuffling is random.
article_snippet: Dr Diaconis said that there are a staggering 80,658,175,170,943,878,571,660,636,856,403,766,975,289,505,440,883,277,824,000,000,000,000 configurations in a perfectly random deck.
article_snippet: One way of defining randomness is that all card configurations should be equally likely.
article_snippet: Dr Diaconis said that if a deck of cards is perfectly shuffled, you may expect to guess between four and five cards correctly as they are pulled out one by one from a pack.
article_snippet: But if they are not shuffled enough – for example, if a pack is riffle shuffled four times instead of seven - people might guess nine or ten cards correctly.
highlights_snippet: A Stanford University mathematician compared  shuffling techniques .
  