What has lots of eyes, but can’t see?

I am white when I am dirty, and black when I am clean. What am I?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

Below toothpicks/matchsticks indicate the group of fishes moving from west to east direction. Can you make them move from east to west by just moving three toothpicks/matchsticks?

A boy and a girl are sitting on the porch.
"I'm a boy," says the child with black hair.
"I'm a girl," says the child with red hair.
If at least one of them is lying, who is which?

How many times can you subtract the number two from the number fifty?

Can you find the missing number in the third row?
35 20 14
27 12 18
5 2 ?

John was piloting a plane behind a car but was never able to overtake it. Why?

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Can you find a seven digit number which describes itself. The first digit is the number of zeros in the number. The second digit is the number of ones in the number, etc. For example, in the number 21200, there are 2 zeros, 1 one, 2 twos, 0 threes and 0 fours.