Keys and Locks

Discrete Mathematics Level 2

Each of the four distinct keys below fits exactly one of the four locks. In the worst case scenario, how many times do you have to test a key in a lock in order to match up all the locks and keys?

Note: You do not need to open the locks. You only need to match the locks to their keys.

Excel in math and science

Master concepts by solving fun, challenging problems.

It's hard to learn from lectures and videos

Learn more effectively through short, interactive explorations.

Used and loved by over 5 million people

Learn from a vibrant community of students and enthusiasts, including olympiad champions, researchers, and professionals.