Question 8
A pirate island is divided into sixteen regions numbered 1–16, exactly one of which contains treasure. Captain Boris can enter any set of region numbers into a device, which answers whether the treasure is in one of those regions. For example, entering 1,5,12 and getting “yes” means it is in region 1,5 or 12. What is the smallest number of uses that guarantees Boris can always identify the treasure’s region?