# Exercise 2.5

Following the representation of a pair in this exercise we can define the `cons`

procedure with the `expt`

primitive (you can easily create your own `expt`

procedure though).

A power of 2 is even and a power of 3 is odd (we can easily prove that with mathematical induction) so we can define the `car`

and `cdr`

procedures counting the number of times we can divide by 2 or 3 the pair represented by an integer.