There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

You need to climb ten stairs. At every stair, you can either take one step up or you can jump two steps up.

In how many different ways you can climb 10 stairs?

How can you make a TV, a bed, a dog, and a car liquid?

What is the next number in this matchsticks series riddle?

You walk into an old horror house. It has no power or plumbing. Once inside, you see three doors. Each door has a number on it. Behind each door is a way for you to die. Behind door number one, you die by getting eaten by a lion. Behind door number two, you die by getting murdered. Behind door number three, you die by an electric chair. You can’t turn back, so you have to go through a door. Which door do you go through?

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

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

81 x 9 = 801. What must you do to make the this equation true?

There is a unique number which when multiplied by any number from 1 to 6, we will get the new number that contains the same digits only.

Can you find that number?