## Holiday Reading: Alex’s Adventures in Numberland

Here’s another holiday reading idea that we had: **Alex’s Aventures in Numberland**** **by Alex Bellos. This is a popular Maths title – remarkably, the hardback edition has now spent several months in the **Amazon Top 100 books** (no.73 when we checked today).

Worth a look, we thought…

And, as it turns out, worth a read.

First chapter goes back to the origin of counting. Turns out that some Amazonian tribes don’t count beyond 5. In fact, Stone Age Man (and modern children, come to that) tend to think of numbers *logarithmically*. That’s to say: they perceive the gap between 10 and 100 as being the same size as the gap between 100 & 1000. That’s a striking observation that turns out to be more logical than it seems. As Bellos points out, our spatial perception is logarithmic. An object 1km away does not seem to be 10 times the distance of an object 100m away – more like twice the distance.

As children grow older, they perceive numbers in an increasingly “normal” way. (Mind you – a colleague pointed out that that process appeared to go into reverse again during the Credit Crunch and bank bail-out… £1bn needed? £10bn anyone?) The chapter moves on in pleasantly random fashion to look at the counting skills of chimpanzees (rather impressive as it happens) and other delightful digressions.

**Did you know?**

Another favorite bit is in Chapter 4 on mathletes and human calculators. The various world records in this field are all as startling as each other. For example, Alberto Coto holds the record for the fastest mental multiplication of eight digit numbers. He took 8 minutes & 25 seconds to perform 10 multiplications of two 8-digit numbers… Not very useful, but certainly quick. Another that has attracted interest (and a few headlines) is Frenchman Alexis Lemaire who, in 2007, took just 70 seconds to calculate the 13th root of a 200 digit number. (For reference: it takes about 70 seconds to read out a 200 digit number.) It should be said, this is considered by some more a feat of memory than calculation.

There are plenty of reviews available. Here’s one in **the Guardian**, and here’s another in **the Independent**.

Next up on our holiday reading list: Michael Brook’s **13 Things That Don’t Make Sense – The most intriguing scientific mysteries of our times** (not strictly Maths, but not far off).

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