I am learning now the numbers in Spanish, but I would like to understand something.
When I see the numbers names between 11-19 in Spanish, then I've noticed that is a portmanteau of the number plus the suffix "ce".
Once is 11, because it is uno + the suffix "ce".
Doce = 12 (doce + "ce")
Trece = 13 (tres + "ce")
Catorce = 14 (cuatro + "ce")
But when we come to number 15, unlike the previous numbers, then I don't find the explanation of the relation between cinco and the name quince. What is the explanation for that?