math

Prime Number

A natural number greater than 1 that has no positive divisors other than 1 and itself.

A prime number can only be divided evenly by 1 and itself. The first 10 primes: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29.

Key Facts

  • 2 is the only even prime number
  • There are infinitely many primes (proved by Euclid ~300 BC)
  • Every integer > 1 can be uniquely factored into primes (Fundamental Theorem of Arithmetic)

Primality Testing

To check if n is prime, test divisibility by all primes up to √n. If none divide evenly, n is prime.

Related Calculators

📊 Prime Number Calculator

Related Terms

Percentage

A number expressed as a fraction of 100, used to describe proportions and rates of change.

Standard Deviation

A measure of the spread or dispersion of a data set from its mean (average).

Mean, Median, and Mode

Three measures of central tendency used to describe the center of a data set.

Pythagorean Theorem

A fundamental relation in geometry: the square of the hypotenuse equals the sum of squares of the other two sides.

Area and Perimeter

Area measures the surface inside a shape (in square units); perimeter measures the distance around it.

Fractions

A number representing a part of a whole, written as a numerator over a denominator.