If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

The sum of a mother, her baby and her dog's weight is 170 Kg. How much does the baby weigh if the mother weighs 100 kg more than the combined weight of the baby and the dog, and the dog weighs 60 per cent less than the baby?

I have an eye but still cannot see.

Who am I?

I go up and I go down.
I go up towards the beautiful sky and down toward the green ground.
I am present tense.
I am past tense too
Children love me.

Who Am I?

I am quite hot but become too cold if you remove the first two letters. What am I?

What is black when you buy it, red when you use it, and gray when you throw it away?

Keyboard words are not in alphabetical order, Why?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

There’s a girl who has a large family. She has an equal amount of brothers and sisters, but each brother only has half as many brothers and sisters. What’s the correct amount of brothers and sisters?

A thief is convicted in Mexico. He gets the death penalty. The judge allows him to say the last sentence to determine how the penalty will be carried out. If the thief lies, he will be hanged, if he speaks the truth he will be beheaded. The thief tells the last sentence and to everybody's surprise some minutes later he is set free because the judge cannot determine his penalty. What did the thief say?