Question 75
'ERNIE' is a random number producer. Pi could also be called a random number producer: its decimal expansion is known only to a limited number of places, nobody knows a far-off decimal digit, and each digit has the same chance of being that one. So if you had a number made of random digits, what would be the average difference between two random digits side by side? It 'should' be (0 + 9)/2 = 4.5, but it isn't. What is it?
