The Friday File: This week, the World Memory Championships are being held. The reigning world champion is American Alex Mullen. He holds the world record for the longest sequence of numbers memorized in an hour at 3,029, cards in an hour at 1,626, and numbers in five minutes at 520. Marwin Wallonius holds the record for memorizing the longest string of binary numbers in 30 minutes at 5,040. Wow!