Two guards were on duty outside a barracks. One faced up the road to watch for anyone approaching from the North. The other looked down the road to see if anyone approached from the South. Suddenly one of them said to the other, "Why are you smiling?"

How did he know his companion was smiling?

Count the number of squares in the picture below.

Considering the below equation:

V + II - VI = 10
IV - X + VIII = 20
IV - VII + VI = 30

Then, I + II + III = ?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

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

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

The following alphametic has only one solution. Can you find it?
ENLIST + SILENT + LISTEN = ANAGRAM

PS: You may start the number from 0.

Can you quickly find which two matchstick figures are identical?

You are in a land where thirty men and two women were dressed in classic black and white dresses.
They begin to fight as soon as any of them move.

Where are you?

What do you call a fish without an eye?