Logic Riddles

Question: A man finds a small iron coin dated 154 B.C., what's it worth?

Question: I'm number three.
But I'm not a number.
I'm hot and cold at the same moment but not at the same time.
I'm number three.
But I'm not a number.

Who or what am I?

Question: When is 1500 plus 20 and 1600 minus 40 the same thing?

Question: What English word is always spelled incorrectly?

Question: How can you make a TV, a bed, a dog, and a car liquid?