prolog function/predicate examples

Defining four functions (it’s called predicates in prolog), addition, subtraction, multiplication, and division. Each of them takes three parameters, the result is saved to the third parameter.
[code language=”text”]
addition(A, B, C):- C is A + B.
subtraction(A, B, C):- C is A – B.
multiplication(A, B, C):- C is A * B.
division(A, B, C):- C is A / B.
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Assume the above code is in a file called functions.pl, load the file in prolog and run the following queries in prolog console. X is passed in as a variable holder, the result will be saved to X when the function returns.
[code language=”text”]
?- addition(2,3,X).
X = 5.

?- subtraction(4,2,X).
X = 2.

?- multiplication(3,4,K).
K = 12.

?- division(9, 3, D).
D = 3.
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