Why is the Hole below a Lock?

what's the probability of getting a king or a queen from a pack of 52 cards?

Can you calculate the probability of getting a sum of six when a dice is thrown twice?

Begin with a word, five letters to my name,
Remove the first and last but I am the same
Take out my middle and still, I remain.
What word am I?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

A few friends are enjoying their sea voyage in a boat full of apples. On the way, they felt hungry and thus decided to eat the apples. Together, they ate two dozen of apples. When they have eaten the apples, will there be any change in the water level?

The centre of the third figure is empty. What digit should fit inside?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

You have three orange, two pink and five purple balls in the drawer beside your bed. There is no electricity and the room is entirely dark. How many balls must you take out to ensure at least one ball of each colour at least?

I travel all around the world but always stay in the corner. What am I?