What is next number in the pattern below:

131 517 192 123 ?

A girl was sitting in her hotel room when she heard a knock on the door. She opened the door and found that a man was standing outside.
The man said, "Oh! I am really sorry, I thought this was my room."
He then walked through the corridor to the elevator. The girl did not know the man. She closed her door and called security asking them to apprehend the man.
What made her suspicious of that man? He might have been genuinely mistaken.

Two old friends, Jack and Bill, meet after a long time.

Three kids
Jack: Hey, how are you, man?
Bill: Not bad, got married and I have three kids now.
Jack: That's awesome. How old are they?
Bill: The product of their ages is 72 and the sum of their ages is the same as your birth date.
Jack: Cool..But I still don't know.
Bill: My eldest kid just started taking piano lessons.
Jack: Oh, now I get it.

How old are Bill's kids?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

It belongs to you, but other people use it more than you do. What is it?

Solve this tricky question. You are trapped in a forest. With you, you have a gun preloaded with two bullets in it. In front of you, there is a tiger, a leopard and a jaguar.

How do you survive?

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

Can you find the six hidden animals in the picture below?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?