This is a "PRI" puzzle that was posted on a reddit question. https://www.reddit.com/r/cognitiveTesting/comments/1btdot2/has_anyone_got_any_hard_pri_puzzles/
This is a "PRI" puzzle that was posted on a reddit question. https://www.reddit.com/r/cognitiveTesting/comments/1btdot2/has_anyone_got_any_hard_pri_puzzles/