What happened? Historical brainpuzzle

What happened in the middle of the twentieth century that will not happen again for 4,000 years?

Series and numbers

Which will be last number of series?
18, 46, 94, 63, 52, ?

We want to cut a 3-inch cube into 27 1-inch cubes. We can do this by making six cuts, as shown. Can we accomplish the task with fewer cuts by rearranging the pieces between cuts?

Following the serie

What are the next two letters in the following series and why?

W A T N T L I T F S _ _

Against the law

Why is it against the law for a man living in Madrid to be buried in Barcelona?

clock puzzle

Over a 24 hour period, how many times will the minute and hour hand on the 24hr clock form a right angle?