What does it mean?

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

If six children and two dogs were under an umbrella, how come none of them got wet?

What numbers should go on the bottom line?
3 6 9 15
8 2 10 12
11 8 19 27
19 10 29 39
? ? ? ?

A convention is held where all the big logicians are summoned. The master places a band on everyone's forehead. Now all of them can see others bands but can't see his own. Then they are told that there are different colours of bands. All the logicians sit in circle and they are further explained that a bell will ring at regular intervals. The moment when a logician knew the colour of band on his forehead, he will leave at the next bell. If anyone leaves at the wrong bell, he will be disqualified.

The master assures the logicians that the puzzle will not be impossible for anyone of them. How will the logicians manage ?

What number do you get when you multiply all of the numbers on a telephone's number pad?

Solve the counting riddle by identifying the number of triangles in the given picture.

You’ll find me on Mercury, Earth, Mars, Jupiter, Saturn, and Uranus. But never Neptune, or Venus. What am I?

Find the missing number in the sequence below:

Take one out and scratch my head, I am now black but once was red. What am I?