Answer: 180 degrees
The angles of a triangle always sum to 180 degrees.

Answer: 160

Answer: 4 trivial factors.
The positive +1 and +N and the negative -1 and -N.

Answer: Leonhard Euler.
Swiss-born Euler is held to be one of the greatest mathematicians in history. He made pioneering contributions to several branches of mathematics and introduced much of the modern mathematical terminology and notation.

Answer: Paul Erdős
Erdős published at least 1,525 mathematical papers during his lifetime. He engaged more than 500 collaborators and devoted most of his time to mathematics up until his death in 1996 at the age of 83 years old.

Answer: Pierre-Simon Laplace has an Erdős number of at most 14!
According to "The Erdös number project" a path to Laplace was found by Leonid Yanushevich giving the famous mathematician an Erdös number of at most 14.

Answer: Paul Erdős, of course!
As the Erdős number describes the "collaborative distance" in authorship of mathematical papers between mathematician Paul Erdős and another person it is only natural that Paul Erdős holds this position.

Answer: 49

Answer: 4275

Answer: 91