The internal data structure for rational numbers is
`rat(`

`Num``,`

`Den``)`

. `Den` is always positive, i.e.
the sign of the rational number is the sign of `Num`. Further,
`Num` and `Den` are relative prime. Note that integer `N`
looks like `rat(`

`N``,1)`

in this representation. You can
control printing of terms with `portray/1`

.