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

It belongs to you, but other people use it more than you do. What is it?

When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

There are three boxes which are labeled as Rs100, Rs150, and Rs200. One box contains two notes of Rs. 50. The second box contains one note of Rs50 and one note of Rs100 The third box contains two Rs. 100 notes. All boxes are labeled incorrectly.

What is the minimum number of boxes you must check in order to label all boxes correctly?

What 5-letter word typed in all capital letters can be read the same upside down?

A sundial has the fewest moving parts of any timepiece. Which has the most?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

There was once a college that offered a class on probability applied to the real world. The class was relatively easy, but there was a catch. There were no homework assignments or tests, but there was a final exam that would have only one question on it. When everyone received the test paper it was a blank sheet of paper with a solitary question on it: 'What is the risk?'.Most students were able to pass, but only one student received 100% for the class! Even stranger was that he only wrote down one word!
What did he write?

Complete the series by replacing "?" with the correct number.

ST ND RD TH '?'

The answer I give is yes, but what I mean is no. What was the question?