Good Riddles

Question: Like a middle pillar I stand among 6, all 9 of my characters make me the largest to exist.

Question: There were 10 horses and 9 paddocks. How do you fit all 10 horses in the paddocks with only 1 allowed in each paddock?

Question: Pretend walls have their own civilization. Each wall is a different country with different culture. One wall has its own animal, one wall has its own nut, and one wall has its own street. What are the three things the walls own?

Question: Keys! keys! So many keys, When F is involved The key note is _ ?

Question: When people cut me, I do not bleed. They use me, but then they leave. I die, but then revive. I change my appearance as time goes by. What am I?