Riddle #1051

Five add six is eleven, but six add seven is one. How is that possible?

I live in a hotel, on the land or in the sea, whatever could I be?

I am a large cat, but I don't meow. I have a loud roar that can be heard from miles away. Who am I?

I have a headboard but no brain, and a footboard but no toes. You visit me to travel to worlds that don't exist. What am I?

I come in many colors and I'm often in a wrap. I am a dentist's trap. Children love to eat me, but they shouldn't have too many. What am I?

I am sweet and tasty, sometimes hard or chewy. I wear a bright paper coat that is noisy and crinkly. Who am I?

I am a giant sandbox built by nature. I have a coat of gold and a hem of blue, and I am the favorite place for a holiday view. What am I?

I am known as a king, and the jungle's where I reign. It is hard to tame me, and I have a large mane. Who am I?

This old one runs forever, but never moves at all. He has not lungs nor throat, but still a mighty roaring call. What is it?

You bury me when I am alive, and dig me up when I die. What am I?

Before Mt. Everest was discovered, what was the highest mountain in the world?