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Mathematics in Africa has been written out of history books – it’s time we reminded the world of its rich past

In Trinidad and Ghana, it’s known as susu. In Senegal and Benin it’s tontines. In Nigeria, where it began in the 1700s, it’s esusu. Whatever you call it, this system of large-scale money-pooling for mutual benefit shows that Africa has never had a problem with mathematics.

When we learn the history of mathematics, we tend to learn about the achievements of Greek, Hindu, Chinese and Arabic civilisations. If we learn anything about African mathematics, it’s almost entirely about Egypt. But sub-Saharan Africa has a rich mathematical history too – and it is possible that the world’s museums hold the key to bringing it back to life.

Some of the evidence comes from those who were in contact with slaves and slavers. European captains of slave-trading ships, for instance, marvelled at the mathematical abilities of the African traders they encountered. Sailors who made bargains with African slave dealers described them as “sharp arithmeticians” who could skillfully convert currencies and exchange rates in their heads. According to one account, a broker might have 10 slaves to sell, “and for each of these he demands 10 different articles. He reduces them immediately by the head into bars, coppers, ounces, according to the medium of exchange that prevails in the part of the country in which he resides, and immediately strikes the balance”.

That shouldn’t surprise us when we look at the number system used in the Yoruba language spoken in what is now Nigeria. The phrase for “forty-five” translates as “take five and 10 from three twenties”. It might sound cumbersome, but it is a sign of a people comfortable with subtraction and multiplication. The Yoruba started esusu too. Records of complex financial systems in pre-colonial Nigeria – banks and mutual societies, effectively – suggest that dealing with complicated accounts, loans, credits and debits was just part of everyday life. These were not people who were uncomfortable with mathematics.

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