Yan, tyan, tethera - counting systems above Ullswater

 

We found three stones celebrating the local counting system for sheep https://en.wikipedia.org/wiki/Yan_Tan_Tethera I have been aware of it but haven't thought about it much. I hadn't been aware that it was base-20. Then I remembered that Gaelic has a counting system based on fichead, which is twenty. Base-20 turns out to be called Vigesimal . There are many examples and it does turn up in English in the word "score" as in "three score years and ten".