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

What goes up but never comes down?

Can you find out which number multiplied by itself will give the output as 12345678987654321?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?

Four cars come to a four-way stop, each coming from a different direction. They can’t decide who got there first, so they all go forward at the same time. All 4 cars go, but none crash into each other. How is this possible?

In the given figure, move three matchsticks so that the resulting figure contains two rectangles.

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

The following four words might seem abrupt to you. But you can make them meaningful by just adding vowels.
RDSH
GGPLNT
TMT
NN

Hint: All of them are vegetables.

John's five friends Rachel, Jacob, Phoebe, Joey and Chandler live on the same road.

Rachel lives in the house: A, Jacob lives in the house: B, Phoebe lives in the house: C, Joey lives in the house:D, Chandler lives in the house: E

Mathematically
B*C*D = 1260
B + C + D = 2E
2A = E

The road numbers run from 2 to 222.

Can you tell me the house number of each of John's friends?

They are the five precious gems of an everyday sort and all can be found on a Tennis Court. Who are they?