Logic Riddles

Question: Most people are born on one, die on one, and experience some of their most blissful moments upon it.

Question: I am unseen but all people know of me. I am intangible yet sharper than any sword. I come from nothingness but can fell even the mightiest kings.

Question: In the middle of winter, a woman is found dead in her bed, with multiple stab wounds in the stomach. Soaked into the sheets is a massive amount of blood, along with blood drops on the carpet. On the side table beside her bed, there is a glass full of water mixed with blood. What was the murder weapon, where is it now, and how was she killed?

Question: In the middle of winter, a woman is found dead in her bed, with multiple stab wounds in the stomach. Soaked into the sheets is a massive amount of blood, along with blood drops on the carpet. On the side table beside her bed, there is a glass full of water mixed with blood. What was the murder weapon, where is it now, and how was she killed?

Question: The 22nd and 24th Presidents had the same biological mother and father, but weren't brothers. They were both male, and were never female. Neither were adopted or "switched at birth". How is this possible?