Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

What does this rebus mean?

O
N
C
E
TIME

How can I get the answer 24 by only using the numbers 8,8,3,3?

You can use the main signs add, subtract multiply and divide.

The first person saw the bridge step on it and crossed,
the second person saw the bridge did not step on it but crossed,
the third person did not see the bridge did not step on it but crossed.
Who are these people?

My location can be determined by the below rebus.
So where am i ?

What do you see in the image below

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.

The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?

On a certain day, John celebrated his birthday. Two days later, his older twin brother Jacob celebrated his birthday.

Is this even possible? How can it be?

What is full of holes but still holds water?