?- consult('arithmetic.pro').
true.

?- declear(a,10).
true.

?- declear(b,20).
true.

?- display_bindings.
a -> 10
b -> 20
true.

?- sub(a,b,c).
true.

?- display_bindings.
a -> 10
b -> 20
c -> -10
true.

?- mul(a,c,d).
true.

?- display_bindings.
a -> 10
b -> 20
c -> -10
d -> -100
true.

?- div(a,b,e).
true.

?- display_bindings.
a -> 10
b -> 20
c -> -10
d -> -100
e -> 0.5
true.

?- exp(a,e,f).
true.

?- display_bindings.
a -> 10
b -> 20
c -> -10
d -> -100
e -> 0.5
f -> 3.1622776601683795
true.

?-