Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

In which direction should the missing arrow point?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

People are waiting in line to board a 100-seat aeroplane. Steve is the first person in the line. He gets on the plane but suddenly can't remember what his seat number is, so he picks a seat at random. After that, each person who gets on the plane sits in their assigned seat if it's available, otherwise, they will choose an open seat at random to sit in. The flight is full and you are last in line. What is the probability that you get to sit in your assigned seat?

A plane crashed between the border of Mexico and America. Where do you bury the survivors?

If you had an infinite supply of water and 5-quart and 3-quart pails, how would you measure exactly 4 quarts? What is the least number of steps you need?

When I asked a girl's name she told me her name is the date '07/09/2001'.

I thought for a few seconds and then I got her name. Do you?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

Using Only Five 5's and any mathematical operator make sum as 37

There is a place where if I stand up straight, I will still be considered sideways.