##### Two metal rods: Only one is magnetic (hard)

By Martin Gardner

Question: You are in a room with two metal rods and no other metal. One of them is magnetized and the other is not.

How can you determine which one is magnetized and which is not?

##### 100 blue eyes island (hard)

Question: There is an island with exactly 201 residents, 100 with blue eyes, 100 with brown eyes, and the island leader (who has green eyes). To leave the island, one must know their own eye color. There are no reflective surfaces on the island and no on can communicate with each other other than the leader to the residents. No one on the island knows how many of each eye color there is. Everyone on the island is a perfect logician, meaning that if there us a solution they'll find it. Every morning the leader gives anyone a chance to leave the island by guessing their eye color. One morning, the leader gathers all 200 residents to make an announcement, he says "at least 1 person on this island has blue eyes" How many people leave the island and in how many days after the announcement? Notes: this is known as one of the hardest riddles ever

##### All rung up (hard)

Question: In the harbor of a small town, there is a large boat. Coming off of the boat is a ladder reaching down so that the bottom rung is just above the surface of the water. As the tide comes in, the water rises at 1 foot every 30 minutes, and continues like this for 3 hours. If the rungs are each 1 foot apart, how many rungs are under water when the tide stops rising?

##### What word is shorter when you add letters to it (medium)

By jBoner

Question: What word is shorter when you add two letters to it?

##### Hard Riddle #4 (medium)

Question: What starts with the letter "t", is filled with "t" and ends in "t"?

##### How many months have 28 days (medium)

Question: 7 months have 31 days. How many months have 28 days?

##### What kind of room has no doors or windows (medium)

Question: What kind of room has no doors or windows?

##### Hard Riddle #16 (medium)

Question: I can run but never walk. Wherever I go, thought are close behind me.

What am I?

##### Hard Riddle #23 (medium)

Question: Whoever makes it, tells it not. Whoever takes it, knows it not. Whoever knows it, wants it not.

What is it?

##### Hard Riddle #24 (medium)

Question: I fly, yet I have no wings. I cry, yet I have no eyes. Darkness follows me; lower light I never see.

What am I?