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# Four fours

Four fours is a mathematical puzzle. [1]

Addition (often signified by the plus symbol "+") is one of the four elementary, mathematical operations of arithmetic, with the others being subtraction, multiplication and division.

## Bracket

A bracket is a tall punctuation mark typically used in matched pairs within text, to set apart or interject other text.

## Cube root

In mathematics, a cube root of a number x is a number a such that a3.

## Derangement

In combinatorial mathematics, a derangement is a permutation of the elements of a set, such that no element appears in its original position.

## Division (mathematics)

In mathematics, especially in elementary arithmetic, division (denoted ÷ or / or —) is an arithmetic operation.

## Elementary arithmetic

Elementary arithmetic is the simplified portion of arithmetic that includes the operations of addition, subtraction, multiplication, and division.

## Exponentiation

Exponentiation is a mathematical operation, written as bn, involving two numbers, the base b and the exponent n. When n is a positive integer, exponentiation corresponds to repeated multiplication of the base: that is, bn is the product of multiplying n bases: In that case, bn is called the n-th power of b, or b raised to the power n. The exponent is usually shown as a superscript to the right of the base.

## Expression (mathematics)

In mathematics, an expression (or mathematical expression) is a finite combination of symbols that is well-formed according to rules that depend on the context.

## Factorial

In mathematics, the factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n. For example, The value of 0! is 1, according to the convention for an empty product.

## Gamma function

In mathematics, the gamma function (represented by the capital Greek letter Γ) is an extension of the factorial function, with its argument shifted down by 1, to real and complex numbers.

## Hash table

In computing, a hash table (hash map) is a data structure used to implement an associative array, a structure that can map keys to values.

## Krypto (game)

Krypto is a card game designed by Daniel Yovich in 1963 and published by Parker Brothers and It is a mathematical game that promotes proficiency with basic arithmetic operations.

## Logarithm

In mathematics, the logarithm is the inverse operation to exponentiation.

## Mathematical puzzle

Mathematical puzzles make up an integral part of recreational mathematics.

## Memoization

In computing, memoization is an optimization technique used primarily to speed up computer programs by storing the results of expensive function calls and returning the cached result when the same inputs occur again.

## Multiplication

Multiplication (often denoted by the cross symbol "×", by a point "·" or by the absence of symbol) is one of the four elementary, mathematical operations of arithmetic; with the others being addition, subtraction and division.

## Multiplicative inverse

In mathematics, a multiplicative inverse or reciprocal for a number x, denoted by 1/x or x&minus;1, is a number which when multiplied by x yields the multiplicative identity, 1.

## Natural number

In mathematics, the natural numbers (sometimes called the whole numbers): "whole number An integer, though sometimes it is taken to mean only non-negative integers, or just the positive integers." give definitions of "whole number" under several headwords: INTEGER … Syn. whole number.

## Percentage

In mathematics, a percentage is a number or ratio expressed as a fraction of 100.

## Repeating decimal

A repeating or recurring decimal is a way of representing rational numbers in base 10 arithmetic.

## Richard A. Proctor

Richard Anthony Proctor (23 March 1837 – 12 September 1888) was an English astronomer.

## Square (algebra)

In mathematics, a square is the result of multiplying a number by itself.

## Square root

In mathematics, a square root of a number a is a number y such that, in other words, a number y whose square (the result of multiplying the number by itself, or) is a. For example, 4 and −4 are square roots of 16 because.

## Subtraction

Subtraction is a mathematical operation that represents the operation of removing objects from a collection.

## W. W. Rouse Ball

Walter William Rouse Ball, known as W. W. Rouse Ball (14 August 1850 – 4 April 1925), was a British mathematician, lawyer, and fellow at Trinity College, Cambridge from 1878 to 1905.

## 4 (number)

4 (four) is a number, numeral, and glyph.

## References

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