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Mathematica Teacher's Edition

Built-in Functions

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PrimeQ

PrimeQ[expr] yields True if expr is a prime number, and yields False otherwise.

PrimeQ[1] gives False.
PrimeQ[-n], where n is prime, gives True.
PrimeQ[n, GaussianIntegers->True] determines whether n is a Gaussian prime.
Simplify[expr Primes] can be used to try to determine whether a symbolic expression is mathematically a prime.
See The Mathematica Book on the web: Section 2.3.5, Section 3.1.1 and Section 3.2.4.
Implementation Notes: see Section A.9.4.
See also: FactorInteger, Primes.

Further Examples