What happened when the wheel was invented?

Open a Laptop which is password protected. Hint for the password is given as below:

1 mobile 3 books 2 Boards 1 night 4 balls 2 lighters 1 ghost 1 hat 3 watches

Two friends decide to get together; so they start riding bikes towards each other. They plan to meet halfway. Each is riding at 6 MPH. They live 36 miles apart. One of them has a pet carrier pigeon and it starts flying the instant the friends start traveling. The pigeon flies back and forth at 18 MPH between the 2 friends until the friends meet.

How many miles does the pigeon travel?

Which is faster, Heat or Cold ? Explain.

How can you take 2 from 5 and leave 4?

Why is it against the law for a man living in Delhi to be buried in Mumbai?

Which alphabet letter is a question?

A number can be multiplied by multiple of nine
i.e 9 18 27 36 45 ...

and the resulting number consist of only one digit.

Can you identify the number ?

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

Replace the question mark with the number below given a simple math problem.