What is the formula to calculate Pi?

I have studied many books on maths, but haven't found the formula

What are the hardest Math Concepts to grasp?

What is the greatest achievement of mathematics we have accomplished in the last 10 years?

How do you prove the Twin Prime Conjecture?

A little Test, Members?

A few difficult Brain teasers 1.) Mr. Black, Mr. Gray, and Mr. White are fighting in a truel. They each get a gun and take turns shooting at each other until only one person is left. Mr. Black, who hits his shot 1/3 of the time, gets to shoot first. Mr. Gray, who hits his …

What is the end point of infinity?

I heard some guy had figured out that the endpoint of infinity was -1/12x or something, can someone explain?