What English word has three consecutive double letters?

A rubber ball keeps on bouncing back to 2/3 of the height from which it is dropped. Can you calculate the fraction of its original height that the ball will bounce after it is dropped and it has bounced four times without any hindrance ?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

Things are just as they seem, right? Well, check again.
Can you count the number of tigers in this picture ?

In the given figure, you can see that four match sticks are used to form a square. Can you form five squares by using six matches?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

If a zookeeper had 100 pairs of animals in her zoo, and two pairs of babies are born for each one of the original animals, then (sadly) 23 animals don’t survive, how many animals do you have left in total?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Three people enter a room and have a green or blue hat placed on their heads. They cannot see their own hat but can see the other hats.
The colour of each hat is purely random. They could all be green, blue, or any combination of green and blue.
They need to guess their own hat colour by writing it on a piece of paper, or they can write 'pass'.
They cannot communicate with each other in any way once the game starts. But they can have a strategy meeting before the game.
If at least one of them guesses correctly they win $10,000 each, but if anyone guesses incorrectly they all get nothing.
What is the best strategy?

I am a normal creature, but I have five hands. I can even have more but even then I will be considered normal.

Who am I?