1. Write a Prolog program to calculate the factorial of a given number.

% Write a Prolog program to calculate the factorial of a given number.

fact(0,1).
fact(N,F):-
(

 % The below is for +ve factorial.
 N>0 ->
 (
  N1 is N-1,
  fact(N1,F1),
  F is N*F1
 )
 ;
 

 % The below is for -ve factorial.
 N<0 ->
 (
  N1 is N+1,
  fact(N1,F1),
  F is N*F1
 )
).

% Output

Prolog Factorial Program