The strange and ancient method of multiplication that Ethiopian merchants used for thousands of years is explained. Using an example of multiplying 11 by 15 and using coffee beans as counters, the method of halving the 11 and ignoring fractions until one is reached, and doubling the 15 the same number of times, is clearly shown. The reason why this works is then outlined as using the powers of two. It turns out that this is linked to the way that modern computers do multiplication too.
As an enrichment clip on methods for multiplication, or extension for those who might be introduced to working in binary.