What is the next number in this series?

4,12,84,3612....

There was an aeroplane crash, every single person died, but two people survived. How is this possible?

Which tank will fill first?

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

The peacock is a bird that does not lay eggs. How do they get baby peacocks?

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

Can you find the thief by just looking at the picture below?

A man always keeps a spare tyre in his car. To make full use of all the five tyres, he changes the tyres in a manner that for a distance of 1, 00,000 km, each of them runs the same distance.

Can you calculate the distance travelled by each tyre on that journey?

Why do we preferably have round manhole covers and not square ones?