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

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

Count the squares in the matchstick puzzle below?

Out of four images which one is the odd one out?

I ask Joseph to pick any 5 cards out of a deck with no Jokers.

He can inspect then shuffle the deck before picking any five cards. He picks out 5 cards then hands them to me (Jack can't see any of this). I look at the cards and I pick 1 card out and give it back to Joseph. I then arrange the other four cards in a special way, and give those 4 cards all face down, and in a neat pile, to Jack.

Jack looks at the 4 cards i gave him, and says out loud which card Joseph is holding (suit and number). How?

The solution uses pure logic, not sleight of hand. All Jack needs to know is the order of the cards and what is on their face, nothing more.

Find out the missing number in the picture attached:

Before Mount Everest was discovered, what was the highest mountain in the world?

You enter your friend's room. He is not in his room. Although you see that on the bed there are two dogs, five cats, two giraffes and three pigs. Also, a couple of chickens and ducks are flying in the room.

Calculate the number of legs standing on the floor.

A and B have a certain number of chocolates with them. If B gives one chocolate to A, they will have an equal number of chocolates. But if A gives one chocolate to B, then A will be left with half the number of chocolates that B has.

Can you find out the number of chocolates they have right now?

There is a wide field of corn. A goose finds its way into the field and starts running. Can you find out till which point the goose can run into the field?