Parsing numbers with multiple digits in Prolog

Question

I have the following simple expression parser:

expr(+(T,E))-->term(T),\"+\",expr(E).
expr(T)-->term(T).

term(*(F,T))-->factor(F),\"*\",term(T).
ter         


        

Answer 1

nat(0). 
nat(N):-nat(N-1).

But you use a syntax that I don't know (see my comment above).