Composite number
A composite number is a positive integer that can be formed by multiplying two smaller positive integers. Equivalently, it is a positive integer that has at least one divisor other than 1 and itself.
Reduced residue system
In mathematics, a subset R of the integers is called a reduced residue system modulo n if: 1.
* gcd(r, n) = 1 for each r in R, 2.
* R contains φ(n) elements, 3.
* no two elements of R are congruent
Table of prime factors
The tables contain the prime factorization of the natural numbers from 1 to 1000. When n is a prime number, the prime factorization is just n itself, written in bold below. The number 1 is called a un
Euler's four-square identity
In mathematics, Euler's four-square identity says that the product of two numbers, each of which is a sum of four squares, is itself a sum of four squares.
Table of divisors
The tables below list all of the divisors of the numbers 1 to 1000. A divisor of an integer n is an integer m, for which n/m is again an integer (which is necessarily also a divisor of n). For example
Divisibility rule
A divisibility rule is a shorthand and useful way of determining whether a given integer is divisible by a fixed divisor without performing the division, usually by examining its digits. Although ther
Integer
An integer is the number zero (0), a positive natural number (1, 2, 3, etc.) or a negative integer with a minus sign (−1, −2, −3, etc.). The negative numbers are the additive inverses of the correspon
Singly and doubly even
In mathematics an even integer, that is, a number that is divisible by 2, is called evenly even or doubly even if it is a multiple of 4, and oddly even or singly even if it is not. The former names ar
Divisor
In mathematics, a divisor of an integer , also called a factor of , is an integer that may be multiplied by some integer to produce . In this case, one also says that is a multiple of An integer is di
Half-integer
In mathematics, a half-integer is a number of the form , where is an whole number. For example, 4+1/2, 7⁄2, −+13/2, 8.5 are all half-integers. The name "half-integer" is perhaps misleading, as the set