What is the fastest way to double your money?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

A Car driver was heading down a street in Washington. He went right past a stop sign without stopping, he turned left where there was a 'no left turn' sign and he went the wrong way on a one-way street. Then he went on the right side of the road past a cop car. Still, he didn't break any traffic laws. Why not?

Can you make four (4) nines (9) equal 100?

There are two words one resembles the "state of rest" and the other is related to "writing/reading material".

Can you name these two words which also sound similar?

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?

You and your two friends are working in a multinational company. How can you three find out the average salary of you all without disclosing your own salary to the other two?

What do you think with the below Picture ?

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

What's a single-digit number with no value?