# One - The most popular number

One is the most popular number, as it appears more often than any other number. More specifically, the first digit of all numbers is a 1 about 30% of the time.

One is the most popular number, as it appears more often than any other number. More specifically, the first digit of all numbers is a 1 about 30% of the time, whereas it is 9 just 4% of time. This was accidentally discovered by the engineer Frank Benford. It works for all numbers - mountain heights, river lengths, populations, etc.

Why? A deep law of mathematics declares that the universe of numbers cannot help avoid the popularity of 1. What is the point? This is a little known law of mathematics, so people faking tax returns will not follow the law and their numbers will start with an even mix of 1s through to 9s. The US tax dept uses Benford's Law to spot frauds. And sharp-eyed teachers can spot children who cheat when they are asked to toss a coin 100 times and note the sequence. Children try to fake the data, but they don't know what the data is supposed to look like. Simon explains how pupils can fake this data successfully and how you can fake your tax return without being caught. (Well, not for this reason at least).

Available now

14 minutes

## Last on

Tue 23 Aug 2005 09:30