# Math

## One Million Digits of Pi

This is primarily a list of Greatest Mathematicians of the Past , but I use 1930 birth as an arbitrary cutoff, and three of the "Top 100" are still alive as I write. Click for a discussion of certain omissions . Please send me e-mail if you believe there's a major flaw in my rankings (or an error in any of the biographies). Obviously the relative ranks of, say Fibonacci and Ramanujan, will never satisfy everyone since the reasons for their "greatness" are different.

## The Thirty Greatest Mathematicians - Aurora

A pseudoprime is a probable prime (an integer that shares a property common to all prime numbers ) that is not actually prime. Pseudoprimes are classified according to which property of primes they satisfy. Some sources use the term pseudoprime about all probable primes, both composite numbers and actual primes. Pseudoprimes are of primary importance in public-key cryptography , which makes use of the difficulty of factoring large numbers into their prime factors. Carl Pomerance estimated in 1988 that it would cost \$10 million to factor a number with 144 digits, and \$100 billion to factor a 200-digit number. [ 1 ] However, finding and factoring the proper prime numbers for this use is correspondingly expensive, so various probabilistic primality tests are used to find primes amongst large numbers, some of which in rare cases incorrectly identify composite numbers as primes.

## Pseudoprime

This article is part of my new book Rediscovering Mathematics , soon out in paperback! How to Read Mathematics by Shai Simonson and Fernando Gouvea Mathematics is “a language that can neither be read nor understood without initiation.” 1 A reading protocol is a set of strategies that a reader must use in order to benefit fully from reading the text.

## How to Read Mathematics - Aurora

A rotor is a convex figure that can be rotated inside a polygon (or polyhedron ) while always touching every side (or face). The least area rotor in a square is the Reuleaux triangle . The least area rotor in an equilateral triangle is a lens with two arcs of circles and radius equal to the triangle altitude .