Benford's Law

An observation about the frequency distribution of leading digits in many real-life sets of numerical data, where in many naturally occurring collections of numbers, the leading significant digit is likely to be small. For example, in sets that obey the law, the number 1 appears as the most significant digit about 30% of the time, while 9 appears as the most significant digit less than 5% of the time. If the digits were distributed uniformly, they would each occur about 11.1% of the time.