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This list contains selected positive numbers in increasing order, including counts of things, dimensionless quantity and probabilities. Each number is given a name in the short scale, which is used in English-speaking countries, as well as a name in the long scale, which is used in some of the countries that do not have English as their national language.
(0.000000000000000000000000000001; 1000−10; short scale: one nonillionth; long scale: one quintillionth)
(0.000000000000000000000000001; 1000−9; short scale: one octillionth; long scale: one quadrilliardth)
(0.000000000000000000000001; 1000−8; short scale: one septillionth; long scale: one quadrillionth)
ISO: yocto- (y)
(0.000000000000000000001; 1000−7; short scale: one sextillionth; long scale: one trilliardth)
ISO: zepto- (z)
(0.000000000000000001; 1000−6; short scale: one quintillionth; long scale: one trillionth)
ISO: atto- (a)
(0.000000000000001; 1000−5; short scale: one quadrillionth; long scale: one billiardth)
ISO: femto- (f)
(0.000000000001; 1000−4; short scale: one trillionth; long scale: one billionth)
ISO: pico- (p)
(0.000000001; 1000−3; short scale: one billionth; long scale: one milliardth)
ISO: nano- (n)
(0.000001; 1000−2; long and short scales: one millionth)
ISO: micro- (μ)
(0.001; 1000−1; one thousandth)
ISO: milli- (m)
(0.01; one hundredth)
ISO: centi- (c)
(0.1; one tenth)
ISO: deci- (d)
ISO: deca- (da)
ISO: hecto- (h)
ISO: kilo- (k)
(10000; ten thousand or a myriad)
(100000; one hundred thousand or a lakh).
(1000000; 10002; long and short scales: one million)
ISO: mega- (M)
(10000000; a crore; long and short scales: ten million)
(100000000; long and short scales: one hundred million)
(1000000000; 10003; short scale: one billion; long scale: one thousand million, or one milliard)
ISO: giga- (G)
(10000000000; short scale: ten billion; long scale: ten thousand million, or ten milliard)
(100000000000; short scale: one hundred billion; long scale: hundred thousand million, or hundred milliard)
(1000000000000; 10004; short scale: one trillion; long scale: one billion)
ISO: tera- (T)
(1000000000000000; 10005; short scale: one quadrillion; long scale: one thousand billion, or one billiard)
ISO: peta- (P)
(1000000000000000000; 10006; short scale: one quintillion; long scale: one trillion)
ISO: exa- (E)
(1000000000000000000000; 10007; short scale: one sextillion; long scale: one thousand trillion, or one trilliard)
ISO: zetta- (Z)
(1000000000000000000000000; 10008; short scale: one septillion; long scale: one quadrillion)
ISO: yotta- (Y)
(1000000000000000000000000000; 10009; short scale: one octillion; long scale: one thousand quadrillion, or one quadrilliard)
(1000000000000000000000000000000; 100010; short scale: one nonillion; long scale: one quintillion)
(1000000000000000000000000000000000; 100011; short scale: one decillion; long scale: one thousand quintillion, or one quintilliard)
(1000000000000000000000000000000000000; 100012; short scale: one undecillion; long scale: one sextillion)
(1000000000000000000000000000000000000000; 100013; short scale: one duodecillion; long scale: one thousand sextillion, or one sextilliard)
(1000000000000000000000000000000000000000000; 100014; short scale: one tredecillion; long scale: one septillion)
(10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000; short scale: ten duotrigintillion; long scale: ten thousand sexdecillion, or ten sexdecillard)
(One googolplex; 10googol; short scale: googolplex; long scale: googolplex)
The number e, known as Euler's number, is a mathematical constant approximately equal to 2.71828, and can be characterized in many ways. It is the base of the natural logarithm. It is the limit of (1 + 1/n)n as n approaches infinity, an expression that arises in the study of compound interest. It can also be calculated as the sum of the infinite series
In computing, floating-point arithmetic (FP) is arithmetic using formulaic representation of real numbers as an approximation to support a trade-off between range and precision. For this reason, floating-point computation is often found in systems which include very small and very large real numbers, which require fast processing times. A number is, in general, represented approximately to a fixed number of significant digits and scaled using an exponent in some fixed base; the base for the scaling is normally two, ten, or sixteen. A number that can be represented exactly is of the following form:
In mathematics and computing, hexadecimal is a positional system that represents numbers using a base of 16. Unlike the common way of representing numbers with ten symbols, it uses sixteen distinct symbols, most often the symbols "0"–"9" to represent values zero to nine, and "A"–"F" to represent values ten to fifteen.
In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a given number x is the exponent to which another fixed number, the base b, must be raised, to produce that number x. In the simplest case, the logarithm counts the number of occurrences of the same factor in repeated multiplication; e.g., since 1000 = 10 × 10 × 10 = 103, the "logarithm base 10" of 1000 is 3, or log10(1000) = 3. The logarithm of x to baseb is denoted as logb(x), or without parentheses, logb x, or even without the explicit base, log x, when no confusion is possible, or when the base does not matter such as in big O notation.
The number π is a mathematical constant. It is defined as the ratio of a circle's circumference to its diameter, and it also has various equivalent definitions. It appears in many formulas in all areas of mathematics and physics. It is approximately equal to 3.14159. It has been represented by the Greek letter "π" since the mid-18th century, and is spelled out as "pi". It is also referred to as Archimedes' constant.
A prime number is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways of writing it as a product, 1 × 5 or 5 × 1, involve 5 itself. However, 4 is composite because it is a product in which both numbers are smaller than 4. Primes are central in number theory because of the fundamental theorem of arithmetic: every natural number greater than 1 is either a prime itself or can be factorized as a product of primes that is unique up to their order.
Benford's law, also called the Newcomb–Benford law, the law of anomalous numbers, or the first-digit law, is an observation about the frequency distribution of leading digits in many real-life sets of numerical data. The law states that in many naturally occurring collections of numbers, the leading digit is likely to be small. For example, in sets that obey the law, the number 1 appears as the leading significant digit about 30% of the time, while 9 appears as the leading significant digit less than 5% of the time. If the digits were distributed uniformly, they would each occur about 11.1% of the time. Benford's law also makes predictions about the distribution of second digits, third digits, digit combinations, and so on.
In poker, the probability of each type of 5-card hand can be computed by calculating the proportion of hands of that type among all possible hands.
Rounding means replacing a number with an approximate value that has a shorter, simpler, or more explicit representation. For example, replacing $23.4476 with $23.45, the fraction 312/937 with 1/3, or the expression √2 with 1.414.
Odds provide a measure of the likelihood of a particular outcome. They are calculated as the ratio of the number of events that produce the outcome to the number that don't. Odds are commonly used in gambling and statistics.
The significant figures of a number written in positional notation are digits that carry meaningful contributions to its measurement resolution. This includes all digits except:
The IEEE Standard for Floating-Point Arithmetic is a technical standard for floating-point arithmetic established in 1985 by the Institute of Electrical and Electronics Engineers (IEEE). The standard addressed many problems found in the diverse floating-point implementations that made them difficult to use reliably and portably. Many hardware floating-point units use the IEEE 754 standard.
1,000,000,000 is the natural number following 999,999,999 and preceding 1,000,000,001. One billion can also be written as b or bn.
In the common parlance, randomness is the apparent lack of pattern or predictability in events. A random sequence of events, symbols or steps often has no order and does not follow an intelligible pattern or combination. Individual random events are by definition unpredictable, but since they often follow a probability distribution, the frequency of different outcomes over numerous events is predictable. For example, when throwing two dice, the outcome of any particular roll is unpredictable, but a sum of 7 will occur twice as often as 4. In this view, randomness is a measure of uncertainty of an outcome, rather than its haphazardness, and applies to concepts of chance, probability, and information entropy.
In computing, quadruple precision is a binary floating point–based computer number format that occupies 16 bytes with precision more than twice the 53-bit double precision.
The hartley, also called a ban, or a dit, is a logarithmic unit which measures information or entropy, based on base 10 logarithms and powers of 10, rather than the powers of 2 and base 2 logarithms which define the bit, or shannon. One ban or hartley is the information content of an event if the probability of that event occurring is 1⁄10. It is therefore equal to the information contained in one decimal digit, assuming a priori equiprobability of each possible value.
In computing, octuple precision is a binary floating-point-based computer number format that occupies 32 bytes in computer memory. This 256-bit octuple precision is for applications requiring results in higher than quadruple precision. This format is rarely used and very few environments support it.
A mathematical constant is a key number whose value is fixed by an unambiguous definition, often referred to by a symbol, or by mathematicians' names to facilitate using it across multiple mathematical problems. Constants arise in many areas of mathematics, with constants such as e and π occurring in such diverse contexts as geometry, number theory, and calculus.