In which direction should the missing arrow point?

If an electric train is travelling south, then which way is the smoke going?

What is next number in the pattern below:

131 517 192 123 ?

Look at the picture and find out which square is not linked with any of the other squares.

There was a strange boy who was born before his father. How can this be possible?

Solve below rebus puzzle?

Find the value of "?" in the ball picture Riddle below:

If 21x = 79x, what is the value of x?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

You are given a set of weighing scales and 12 marbles. The scales are of the old balance variety. That is, a small dish hangs from each end of a rod that is balanced in the middle. The device enables you to conclude either that the contents of the dishes weigh the same or that the dish that falls lower has heavier contents than the other. The 12 marbles appear to be identical. 11 of them are identical, and one is of a different weight. Your task is to identify the unusual marble and discard it. You are allowed to use the scales three times if you wish, but no more. Note that the unusual marble may be heavier or lighter than the others. You are asked to both identify it and determine whether it is heavy or light