It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

Our product and our sum always give the same answer. Who are we?

15 caves are arranged in a circle at the temple of doom. One of these caves has the treasure of gems and wealth. Each day the treasure keepers can move the treasure to an adjacent cave or can keep it in the same cave. Every day two treasure seekers visit the place and have enough time to enter any two caves of their choice.

How do the treasure seekers ensure that they find the treasure in the minimum number of possible days?

What has hands, but can’t clap?

1 rabbit saw 9 elephants while going to the river. Every elephant saw 3 monkeys going toward the river. Each monkey had 1 parrot in each hand. How many animals are going towards the river?

How many times do a clock's hands overlap in a day ?

What occurs twice in a week, once in a year but never in a day?

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

Which point will the car reach to go out?

You find yourself in a strange place guarded by two guards.One of the guard always say truth while other always lies.You don't know the identity of the two.You can ask only one question to go out from there. What should you ask?