This episode is about memorising a pack of cards after they are shuffled. Apart from the fun element, you may never need this skill, and it is very challenging in one way. The reason is that Stephen Fry on QI, recreated the maths based on 52 cards in each deck and the total possible combination. The result would equal 8.06e+67. This number is MASSIVE. On Reddit https://www.reddit.com/r/theydidthemath/comments/1x4mw3/just_how_many_possible_card_combinations_are_there/ it was explained as follows: Say that there exist 10 Billion people on every planet, 1 Billion planets in every solar system, 200 Billion solar systems in every galaxy, and 500 Billion galaxies in the universe. If every single person on every planet has been shuffling decks of cards completely at random at 1 Million shuffles per second since the BEGINNING OF TIME, every possible deck combination would still yet be "shuffled". 

Download the episode transcript to recap what you have learned. Use it or Lose it.