Why Aeroplane windows are round?

What can go up a chimney down, but can’t go down a chimney up?

Can you start the fire using two pieces of wood?

A chicken farmer has figured out that a hen and a half can lay an egg and a half in a day and a half. How many hens does the farmer need to produce one dozen eggs in six days?

Can you find the dog hidden in a group of pandas?

Below is the sum of symbols in each row and column in the figure. Analyzing the figure, can you find out the value of the symbols?

The dirtier I get, the whiter I look. Who am I?

A man is walking down a road with a basket of eggs. As he
is walking he meets someone who buys one-half of his eggs
plus one-half of an egg.
He walks a little further and meets another person who buys
one-half of his eggs plus one-half of an egg.
After proceeding further he meets another person who buys
one-half of his eggs plus one half an egg. At this point, he
has sold all of his eggs, and he never broke an egg.
How many eggs did the man have to start with?

There were five men at church, and it started raining while they were outside. The four that ran still got wet, but the one that was still stayed completely dry. Why did he stay dry?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?