Humans aren’t very good at coming up with numbers off the top of their head—and Iranian officials are apparently no exception according to two academics who looked at the country’s recent election results. The problem? Too many of numbers end with the digit 7 and too few end with the digit 5 to be believable. Under perfectly random conditions, which secret-ballot returns should evince, every digit from 0 to 10 should come up about 10 per cent of the time at the end of a number. (It’s just as likely that an election result from a given province ends in a 2 than it does in a 9.) Iran’s results, on the other hand, show no such distribution. Rather, the numbers end with digit 7 17 percent of the time, and only 4 percent of the results end in the number 5. Furthermore, the last two digits are non-adjacent in only 62 per cent of cases, when they should be non-adjacent in 70 per cent of cases. Together, the results point to one of two things occurring: Iran’s election was either a 1-in-200 long shot mathematical oddity, or the figures were manipulated.

The Washington Post