Quipu https://en.m.wikipedia.org/wiki/Quipu https://en.m.wikipedia.org/wiki/Quipu I remember an article about credit in stores in tiny towns in Spain. It was j

Quipu https://en.m.wikipedia.org/wiki/Quipu https://en.m.wikipedia.org/wiki/Quipu I remember an article about credit in stores in tiny towns in Spain. It was just a rod of wood with some simbol as a signature of the store. Each time you buy something ¿big? they add a mark, and when you get all the ¿10? marks you have to pay with real money. IIRC, the oldest number recorded was some kind of lunar calendar in a bone, wit marks like IIIIIII IIIIIII IIIIIIII IIIIIII IIIIIII IIIIIII IIIIIII IIIIIII Coincidence? (I don't remember the details, but the article was convincing.)