Prime number
A prime is a whole number greater than 1 whose only divisors are 1 and itself: 2, 3, 5, 7, 11, and so on. Every whole number greater than 1 can be written as a product of primes in exactly one way apart from the order of the factors, which is why primes are called the building blocks of arithmetic. Euclid proved that the list of primes never ends, and the pattern in which they appear along the number line is still not fully understood.
Why it matters
Primes are where the simplest questions in mathematics turn out to be the hardest, and modern public-key cryptography depends on that difficulty.
Also written: primes, prime
Where it comes up
Read about Prime number on Wikipedia
Sources
- Prime number Wikipedia
- Prime numbers MacTutor History of MathematicsThe history of what has been asked about primes and how much of it is still open.
