Baseball bat and ball cost $100. If the bat cost $99 more than the ball, what is the cost of each?

A woman is sitting in her hotel room and hears a knock at the door. She opens the door to see a man whom she’s never met before. He says, “I’m sorry, I have made a mistake, I thought this was my room.” He then goes down the corridor and into the elevator. The woman goes back into her room and calls security. What made the woman so suspicious of the man?

Below, you can see three complete equations and one incomplete. Based on the three complete ones, can you complete the incomplete one?

5 $ 4 $ 3 $ 9 = 4215
6 $ 9 $ 2 $ 6 = 3816
4 $ 7 $ 3 $ 3 = 1122
7 $ 2 $ 7 $ 4 = ____

Find the missing number in the sequence below:

John and Jenni are a married couple. They have two kids, one of them is a girl. Assume safely that the probability of each gender is 1/2.
What is the probability that the other kid is also a girl?

Hint: It is not 1/2 as you would first think.

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

Prove that the below maths equation is true.

8 + 8 = 91

Move three sticks of the spiral below to form a square.

What goes through cities and fields, but never moves?

I am the fastest animal but cannot climb the tree. What am I?