Name a key which is hardest to turn.

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

I had an infinite supply of water and 5 litres and 3 litres jars.

How would you measure exactly 4 litres in the least number of steps?

You are given 2 eggs.
You have access to a 100-storey building.
Eggs can be very hard or very fragile means it may break if dropped from the first floor or may not even break if dropped from 100th floor, Both eggs are identical.
You need to figure out the highest floor of a 100-storey building an egg can be dropped without breaking.
Now the question is how many drops you need to make. You are allowed to break 2 eggs in the process

You have a thousand Re. 1 coins with you. You have ten bags with you and you can put any number of coins in each of the bags. The condition is that if someone asks you for any amount between 1 and 1000, you must be able to give that amount by just giving the bag (you are not allowed to open the bag and give coins).

How will you do it?

Today is John's birthday.
A year ago, John had five candles and he lit all the candles except the one at the last.
Now he is going to light all the candles.

How old is John Today?

(He is not five today.....)

How many times can you subtract the number two from the number fifty?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?