What is black when you buy it, red when you use it, and gray when you throw it away?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?

How could a baby fall out of a twenty-story building onto the ground and live?

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?

A beggar on the street can make one cigarette out of every 6 cigarette butts he finds. After one whole day of searching and checking public ashtrays the beggar finds a total of 72 cigarette butts. How many cigarettes can he make and smoke from the butts he found?

What does below Rebus say?

XLR8

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

100 prisoners are stuck in the prison in solitary cells. The warden of the prison got bored one day and offered them a challenge. He will put one prisoner per day, selected at random (a prisoner can be selected more than once), into a special room with a light bulb and a switch which controls the bulb. No other prisoners can see or control the light bulb. The prisoner in the special room can either turn on the bulb, turn off the bulb or do nothing. On any day, the prisoners can stop this process and say "Every prisoner has been in the special room at least once". If that happens to be true, all the prisoners will be set free. If it is false, then all the prisoners will be executed. The prisoners are given some time to discuss and figure out a solution. How do they ensure they all go free?

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?