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One part per hundred is generally represented by the percent sign (%) and denotes one part per 100 (10 2) parts, and a value of 10 −2. This is equivalent to about fourteen minutes out of one day. One part per thousand should generally be spelled out in full and not as "ppt" (which is usually understood to represent "parts per trillion").
The word promille is the cognate in Dutch, German, Finnish and Swedish, and is sometimes seen as a loanword in English with the same meaning as per mille. [7] [4] The symbol is included in the General Punctuation block of Unicode at U+2030 ‰ PER MILLE SIGN. [5] There is also an Arabic-Indic per mille sign at U+0609 ؉ ARABIC-INDIC PER MILLE SIGN.
Conversions between units in the metric system are defined by their prefixes (for example, 1 kilogram = 1000 grams, 1 milligram = 0.001 grams) and are thus not listed in this article. Exceptions are made if the unit is commonly known by another name (for example, 1 micron = 10 −6 metre).
The related concept of permille, or parts per thousand (ppt), means a denominator of 1000, and this parts-per notation is commonly used with larger denominators, such as million and billion, e.g. 75 parts per million (ppm) means that the proportion is 75 / 1 000 000 .
Conversion of units is the conversion of the unit of measurement in which a quantity is expressed, typically through a multiplicative conversion factor that changes the unit without changing the quantity. This is also often loosely taken to include replacement of a quantity with a corresponding quantity that describes the same physical property.
Carbon isotope fractionations are expressed in using delta notation of δ 13 C ("delta thirteen C"), which is reported in parts per thousand (per mille, ‰). [9] δ 13 C is defined in relation to the Vienna Pee Dee Belemnite (VPDB, 13 C/ 12 C = 0.01118) as an established reference standard.
Various ways of expressing fineness have been used and two remain in common use: millesimal fineness expressed in units of parts per 1,000 [1] and karats or carats used only for gold. Karats measure the parts per 24, so that 18 karat = 18 ⁄ 24 = 750 ‰ and 24 karat gold is considered 100% gold.
1 volume percent = 10,000 ppmv (i.e., parts per million by volume) with a million being defined as 10 6. Care must be taken with the concentrations expressed as ppbv to differentiate between the British billion which is 10 12 and the USA billion which is 10 9 (also referred to as the long scale and short scale billion, respectively).