Sometime during every hour the minute hand lies directly above the hour hand. At what time between 4 and 5 o'clock does this happen?
Christmas trees are planted in a rectangular array of 10 rows and 12 columns. The farmer chooses the shortest tree in each of the columns... the tallest tree from each of the rows ... Which is. . . .
Can you explain why every year must contain at least one Friday the thirteenth?