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?

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

Can you identify the direction in which this bus is moving; left or right?

Hint: The bus is moving on the roads of London.

Replace the question mark in the picture below.

As shown in the image, the nine Dogs are square fenced. By constructing just two square fences can you make sure that two Dogs cannot meet each other without crossing the fence?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

Find the number of squares in the below-given picture.

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

A man dies of old age on his 25 birthday. How is this possible?