Fibonacci Series

fib(0,1).
fib(1,1).
fib(N,R):- N >=2,N1 is N-1,N2 is N-2,
 fib(N1,R1),fib(N2,R2),R is R1+R2.

Factorial

fact(0,1).
fact(N,R):-N >0,N1 is N-1,fact(N1,R1),R is N*R1.