What always comes into a house through the keyhole?

What is next number in the pattern below:

131 517 192 123 ?

Can you replace the question mark with the correct number in the below table sequence?

John went to a parrot shop in Mexico, and the parrot owner told him that his parrot is so unique that he repeats everything he hears. John got excited and immediately bought the parrot. John went home and spoke many words, but the parrot does not repeat anything.
He went again to the parrot shop and complaint to the shopkeeper, but the shopkeeper never lied. Explain?

Two-person want to cross a river. Only one boat is present on the riverside that can carry only one person at a time.

However, they still manage to cross the river. How is it possible?

Thirty friends were on a hiking trip when they decided to enjoy the bonfire. They assembled for it and agreed to play a game. For that, they divided themselves into five teams with seven members each, forming five rows.

How did they manage to achieve this formation?

There are forty elephants and they have forty-fore heads. How can this be possible?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

I am the fastest animal but cannot climb the tree. What am I?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?