BBC Radio 4 is broadcasting another series of programmes on numbers. This week’s programme features Benford’s Law which says that in naturally occurring data (so not random number tables) the number 1 appears as the first digit around 30% of the time, which is not what one would expect. It is used to detect forgeries.
You can listen to the programme at A Further Five Numbers and the rest of the series will look at
(Thanks to Gooseania)
You may well have seen those questions which ask “Which is the odd one out?”, and you often get them as part of a so-called intelligence test
What the question really says is “Which one does the questioner think is the odd one out?”. So it becomes a rather more difficult test of trying to read someone else’s mind and nothing to do with your ability to solve a problem.
Here’s an example of a mathematical “odd one out” to show what I mean. Here are 4 ‘true ‘ statements:
- a. 1 + 1 = 0 true in , arithmetic modulo 2
b. 1 + 1 = 2 true in , ring of integers
c. 1 + 1 = 10 true in binary
d. 1 + 1 = 11 true for string concatenation in Basic
The odd one out could be
- b. because it is the only one that is true in
d. because it is the only one that doesn’t involve addition
a. because it is the only one where the right-hand side is less than 1 (using ordering in )
c. because it is the only one where I can’t think of a reason (self-contradictory of course!)
Next time you come across one of those problems, see if you can give a reason why every one of the possibilities could be the odd one out.