What has one letter and starts with an E?

The centre of the third figure is empty. What digit should fit inside?

As you can see that fifteen matches have been used to form an arrangement. What you have to do is remove any six of them to make them ten.

who is silent in the parliament?

Which alphabet letter is a question?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

Can you find the key in the picture below?

There are five people. One of them shot and killed one of the other five.
We know following clues:
1. Dan ran in the NY City Marathon yesterday with one of the innocent men.
2. Mike consider being a farmer before he moved to the city.
3. Jeff is a top notch computer consultant and wants to install Ben new computer next week.
4. The murderer had his leg amputated last month.
5. Ben met Jack for the first time six months ago.
6. Jack has been in seclusion since the crime.
7. Dan used to drink heavily.
8. Ben and Jeff built their last computers together.
9. The murderer is Jack's brother. They grew up together in Seattle.

Consider yourself to be a famous detective "Sherlock Homles", Can you find the killer?

I am white when I am dirty, and black when I am clean. What am I?

I have one of the three numbers: 1, 2, or 3 in my mind. I speak only truth. You can ask me just one question for which I will only reply in yes or no or don't know. What question will you ask from me so that you are able to know the number?