Why do people go to bed?

It has five wheels, though often think four, You cannot use it without that one more, You can put things in it, you can strap things on top, You can't find it in the market, but you can still go shop. What is it?

The person who makes it has no need for it; the person who buys it has no use for it. The person who uses it can neither see nor feel it. What is it?

A new Engineering building containing 100 offices had just been completed. John was hired to paint the numbers 1 to 100 on the doors. How many times will John have to paint the number nine (9)?

When 99 is considered higher than 100?

Can you solve the below tricky visual equation?

A word I know has six letters it contains, remove one letter and 12 remain. What is it?

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?

I look at you, you look at me, I raise my right, you raise your left. What am I?

What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?