its to do with the language.
numbers (i.e. the words for them) in chinese are very regular. (the same goes for slavic languages)
unlike in english, where you have different syntactical rules for forming numbers (e.g. 1-10 are ok, but then you get eleven, twelve (irregular) then 13-19 (quite regular, except thirteen) then an (almost) regular "n-ty m" type expression for the number nm, and so on
whereas in chinese (also slavic) you get a very regular "n-tens m" type expression fpr numbers
this doesnt explain affinity for more abstract level maths, but shows why children are more likely to enjoy maths when they begin learning it (alongside learning language)