考えとく is the te-form → te-form of 考える
Ichidan verb, Transitive verb
to think (about, of); to think over; to ponder; to contemplate; to reflect (on); to meditate (on)
あなたは家族の事を考えるべきです。You must think of your family. to consider; to bear in mind; to allow for; to take into consideration
to think (that); to believe; to hold (a view); to judge; to conclude; to suspect
to intend (to do); to think of (doing); to plan
to predict; to anticipate; to expect; to imagine
to come up with; to think up; to contrive; to devise
to consider (as); to regard (as); to look on (as); to take; to view
Also written 勘える【かんがえる】、稽える【かんがえる】