Good Riddles

Question: How can you add 9 to become 6? (No subtracting).

Question: What has classes but moves?

Question: If you're looking for something sweet I know what to do.
But if you don't like heat I'm not for you.

What am I?

Question: I am a nice word composed of five letters, but the Romans would call me a numbers.

What am I?

Question: A man named Edward was born on December 21st, yet his birthday is during the summer this year.

How could this be?