The Yoruba people have a fascinating and intricate vigesimal (base-20) system of numbering that ingeniously employs subtraction for certain numerical expressions.
In this system, numbers 11-14 are constructed additively, while numbers 15-19 are represented subtractively from 20.
This elegant pattern extends up to 30, and beyond that, each number is articulated as a multiple of 20, with tens and units either added or subtracted. This consistency is maintained until the number 200, after which the system becomes irregular.
Numbers 1-10 in the Yoruba language have unique names:
1 = ikan, 2 = meji, 3 = meta, 4 = merin, 5 = marun, 6 = mefa, 7 = meje, 8 = mejo, 9 = mesan, 10 = mewa.
Additionally, the Yoruba currency system was equally structured: 40 cowries made a string, 2000 cowries a head (or 50 strings), and 20,000 cowries a bag (or 10 heads).
The Yoruba were adept in addition, subtraction, multiplication, and division. However, they did not use negative numbers, as the concept of negative cowries was nonsensical. They also did not have a symbol for zero, interpreting it simply as “nothing,” and decimals were not part of their numeric landscape.
For example:
– 45 is expressed as “five from ten from three twenties,” or (20*3)-10-5.
– 525 is calculated as (200*3)-(20*4)+5, or 600-80+5.
– 300 is represented as 20*(20-5).
In symbolic notation:
– “Ebu” means fraction.
– “Ilopomeji: 2 times
Understanding and studying the intricate Yoruba system requires mathematical expertise. While many Westerners find the system unusual, it remains in use by the Yoruba people today.
This number system is said to have been in existence since at least 1000 AD till date.
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