# Numbers & Symbols Definitions

Browse our growing collection of numbers & symbols definitions:

## Accuracy

Accuracy is how close an approximation is to an actual value. In other terms, in measurement of a set, accuracy refers to closeness of the measurements to a specific value, while precision refers to the closeness of the measurements to each other.

## Alpha (Α, α)

Alpha (Α, α) is the first letter of the Greek alphabet. In the system of Greek Numerals, it has a value of 1.

## Arithmetic

Arithmetic is a branch of mathematics dealing with integers or, more generally, numerical computation. Arithmetic operations include addition, congruence calculation, division, factorization, multiplication, power computation, root extraction, subtraction, logarithms, and calculations involving modulo n.

## Average

An average is a single number taken as representative of a list of numbers. Different concepts of average are used in different contexts.

## Beta (Β, β)

Beta (Β, β) is the second letter of the Greek Alphabet. In the system of Greek Numerals, it has a value of 2.

## Chi (Χ, χ)

Chi (Χ, χ) is the 22nd letter of the Greek alphabet, used to represent the ch sound (as in Scottish loch or German Bauch) in Ancient and Modern Greek. In the system of Greek numerals, it has a value of 600.

## Delta (Δ, δ)

Delta (Δ, δ) is the fourth letter of the Greek alphabet. In the system of Greek numerals it has a value of 4.

## Difference

Difference is the result of subtracting two expressions or numbers (n_{1} - n_{2}), where the minus sign denotes the subtraction. For instance, the difference between 5 and 3 is 5 – 3, which equals 2.

## Epsilon (Ε, ε)

Epsilon (Ε, ε) or lunate ϵ or Greek: έψιλον, is the fifth letter of the Greek alphabet, corresponding phonetically to a mid front unrounded vowel /e/. In the system of Greek numerals it also has the value five.

## Eta (Η, η)

Eta (Η, η) is the seventh letter of the Greek alphabet. Originally denoting a consonant /h/, its sound value in the classical Attic dialect of Ancient Greek was a long vowel [ɛː], raised to [i] in hellenistic Greek, a process known as iotacism.

## Gamma (Γ, γ)

Gamma (Γ, γ) is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3.

## Googol

A googol is a large number equal to 10^{102} or 10^{100}. In other terms, the digit 1 with 100 zeros following it. Written out explicitly, 10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000.

## Googolplex

Googolplex is a large number equal to 10^{10100} or 10^{Googol}. In other terms, the digit 1 with a googol (10^{100}) number of zeros following it.

## Greek Alphabet

The Greek alphabet has been used to write the Greek language since the late ninth or early eighth century BC. It is derived from the earlier Phoenician alphabet, and was the first alphabetic script in history to have distinct letters for vowels as well as consonants.

## Greek Numerals

Greek numerals, also known as Ionic, Ionian, Milesian, or Alexandrian numerals, are a system of writing numbers using the letters of the Greek alphabet.

## Iota (Ι, ι)

Iota (Ι, ι) is the ninth letter of the Greek alphabet. It was derived from the Phoenician letter Yodh.

## Kappa (Κ, κ)

Kappa (Κ, κ) is the 10th letter of the Greek alphabet, used to represent the [k] sound in Ancient and Modern Greek.

## Lambda (Λ, λ)

Lambda (Λ, λ) is the 11th letter of the Greek alphabet, representing the sound /l/. In the system of Greek numerals lambda has a value of 30.

## Mu (Μ, μ)

Mu (Μ, μ) or my is the 12th letter of the Greek alphabet. In the system of Greek numerals it has a value of 40.

## Nu (Ν, ν)

Nu (Ν, ν) is the 13th letter of the Greek alphabet. In the system of Greek numerals it has a value of 50. It is derived from the ancient Phoenician language nun.

## Omega (Ω, ω)

Omega (Ω, ω) is the 24th and last letter of the Greek alphabet. In the system of Greek numerals it has a value of 800.

## Omicron (Ο, ο)

Omicron (Ο, ο) is the 15th letter of the Greek alphabet. In the system of Greek numerals it has a value of 70.

## Phi (Φ, φ)

Phi (Φ, φ) is the 21st letter of the Greek alphabet. In the system of traditional Greek numerals, phi has a value of 500 (φʹ) or 500,000 (͵φ).

## Pi (Π, π)

Pi (Π, π) is the sixteenth letter of the Greek alphabet, representing the sound [p]. In the system of Greek numerals it has a value of 80.

## Psi (Ψ, ψ)

Psi (Ψ, ψ) is the 23rd letter of the Greek alphabet. In the system of Greek numerals it has a numeric value of 700.

## Rho (Ρ, ρ)

Rho (Ρ, ρ) is the 17th letter of the Greek alphabet. In the system of Greek numerals it has a value of 100. It is derived from Phoenician letter res.

## Sigma (Σ, σ)

Sigma (Σ, σ) is the eighteenth letter of the Greek alphabet. In the system of Greek numerals, it has a value of 200. In general mathematics, uppercase Σ is used as an operator for summation.

## Tau (Τ, τ)

Tau (Τ, τ) is the 19th letter of the Greek alphabet. In the system of Greek numerals it has a value of 300.

## Theta (Θ, θ)

Theta (Θ, θ) is the eighth letter of the Greek alphabet, derived from the Phoenician letter Teth. In the system of Greek numerals it has the value 9.

## Triple

Triple means multiplying by three. It is important to note that with regard to some other terms and concepts like vectors and triple product this does not always hold true.

## Trivial

Trivial is related to or being the mathematically most simple case. More generally, the term trivial is used to describe any result which requires little or no effort to derive or prove.

## Truncating a Number

Truncating a number otherwise referred to just as truncation is a method of approximating a decimal number by dropping all decimal places past a certain point without rounding. In other terms truncation is limiting the number of digits right of the decimal point.

## Truncation

Truncation otherwise referred to as truncating a number is a method of approximating a decimal number by dropping all decimal places past a certain point without rounding. In other terms truncation is limiting the number of digits right of the decimal point.

## Twin Primes

A twin prime is a prime number that is either 2 less or 2 more than another prime number. For instance, either member of the twin prime pair 41 and 43.

## Upsilon (Υ, υ)

Upsilon (Υ, υ) or ypsilon is the 20th letter of the Greek alphabet. In the system of Greek numerals, Υʹ has a value of 400.

## Vinculum

Vinculum is a horizontal line placed above multiple quantities to indicate that they form a unit. Oftentimes, it is the horizontal line drawn as part of a fraction or radical, such as ^{a + b}⁄_{a - b} or √ a + b .

## Weighted Average

The weighted average or weighted arithmetic mean is similar to an ordinary arithmetic mean (the most common type of average), except that instead it is used in computing a kind of arithmetic mean of a set of numbers in which some elements of the set carry more importance (weight, frequency, or relative importance) than others.

## Whole Numbers

Whole numbers are any numbers of the set of nonnegative integers. For instance any of the numbers 0, 1, 2, 3, 4, 5, etc.

## Xi (Ξ, ξ)

Xi (Ξ, ξ) is the 14th letter of the Greek Alphabet. In the system of Greek Numerals, it has a value of 60. Xi was derived from the Phoenician letter samekh.

## Zero

Zero is a number which indicates no quantity, size, or magnitude. Zero is the only integer (and the only real number) that is neither a positive or negative value.

## Zeta (Ζ, ζ)

Zeta (Ζ, ζ) is the sixth letter of the Greek Alphabet. In the system of of Greek Numerals, it has a value of 7. It was derived from the Phoenician letter zayin.