8 Out of 10 Cats Does Countdown as part of its 30th anniversary celebrations. Amongst the programmes that were chosen to be merged for the evening of specials, production teams on "Countdown" and "8 Out of 10 Cats" agreed to merge the two formats of their respective programmes together - the crossover between the two formats meant that "Countdown"s arrangement of games would be interspersed with "8 Out of 10 Cats"-style banter. As part of the merger, both Rachel Riley and Susie Dent assumed their roles from the programme, while Jimmy Carr took on the mantle of host, with both Sean Lock and Jon Richardson competing as
8 Out of 10 Cats Does Countdown not consist of the standard 15 rounds. The first few specials had different numbers of rounds ranging from 7 to 10. In the two full series of the show, there were either 8 or 9 rounds. The first three-quarters of the show contained a letters round and a numbers round; the last section had a letters round, a numbers round (if there was time) and a conundrum. More recent series featured rounds involving two contestants participating in humorous activities, such as being blindfolded and identifying props that were spelt with nine letters. The letters and numbers rounds are the same