If eleven plus two equals one, what does nine plus five equal?

A large container is kept in open under the rain. Every passing hour, the water collected inside the container becomes double what it was.

In ten hours, the container is filled completely. Can you calculate how long would it have taken to be filled in half?

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

By moving exactly three matchsticks can you make the below equation true.It can be solved by 3 ways.

In the figure, you can see nine stars. What you have to do is connect all of them by using just four line and without lifting your hand i.e. in a continuous flow.

A and B have a certain number of chocolates with them. If B gives one chocolate to A, they will have an equal number of chocolates. But if A gives one chocolate to B, then A will be left with half the number of chocolates that B has.

Can you find out the number of chocolates they have right now?

If 21x = 79x, what is the value of x?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

Name a key which is hardest to turn.

I welcome the day with a show of light, I stealthily came here in the night. I bathe the earthy stuff at dawn, But by noon, alas! I'm gone.