hcf and factorial

PREDICATES
hcf(integer, integer, integer)
CLAUSES
hcf(X, Y, X):-
Y mod X = 0.
hcf(X,Y,Z):-
S = Y mod X,S<>0, hcf(S, X, Z).
GOAL
hcf(5,10,X).




//FACPTIEAL
PREDICATES
factorial(unsigned,real)
Clauses
factorial(1,1):-!.
factorial(N,FactN):-
M=N-1,
factorial(M,FactM),
FactN=N*FactM.
Goal
factorial(5,F).