ISO 1 is an international standard set by the International Organization for Standardization that specifies the standard reference temperature for geometrical product specification and verification. The temperature is fixed at 20 °C, which is equal to 293.15 kelvins and 68 degrees Fahrenheit.
Due to thermal expansion, precision length measurements need to be made at (or converted to) a defined temperature. ISO 1 helps in comparing measurements by defining such a reference temperature. The reference temperature of 20 °C was adopted by the CIPM on 15 April 1931, and became ISO recommendation number 1 in 1951. It soon replaced worldwide other reference temperatures for length measurements that manufacturers of precision equipment had used before, including 0 °C, 62 °F, and 25 °C. Among the reasons for choosing 20 °C was that this was a comfortable and practical workshop temperature and that it resulted in an integer value on both the Celsius and Fahrenheit scales.
- "ISO 1" | 2013-11-09 | 94 Upvotes 17 Comments
The traditional Burmese units of measurement as of 2010 were still in everyday use in Myanmar (also known as Burma). According to the 2010 CIA Factbook, Myanmar is one of three countries that have not adopted the International System of Units (SI) metric system as their official system of weights and measures. However, in June 2011, the Burmese government's Ministry of Commerce began discussing proposals to reform the measurement system in Burma and adopt the metric system used by most of its trading partners, and in October 2013, Dr. Pwint San, Deputy Minister for Commerce, announced that the country was preparing to adopt the metric system.
Most of the nation uses Burmese units only, although Burmese government web pages in English use imperial and metric units inconsistently. For instance, the Ministry of Construction uses miles to describe the length of roads and square feet for the size of houses, but square kilometres for the total land area of new town developments in Yangon City. The Ministry of Agriculture uses acres for land areas. The Ministry of Foreign Affairs uses kilometres (with mile equivalents in parentheses) to describe the dimensions of the country.
- "Myanmar units of measurement" | 2017-10-25 | 17 Upvotes 13 Comments
The yottabyte is a multiple of the unit byte for digital information. The prefix yotta indicates multiplication by the eighth power of 1000 or 1024 in the International System of Units (SI), and therefore one yottabyte is one septillion (one long scale quadrillion) bytes. The unit symbol for the yottabyte is YB. The yottabyte, adopted in 1991, is the largest of the formally defined multiples of the byte.
- 1 YB = 10008bytes = 1024bytes = 1000000000000000000000000bytes = 1000zettabytes = 1trillionterabytes
A related unit, the yobibyte (YiB), using a binary prefix, is equal to 10248bytes (approximately 1.209 YB).
- "Yottabyte" | 2013-06-10 | 53 Upvotes 40 Comments
The long hundred, also known as the great hundred or twelfty, is the number that was referred to as "hundred" in Germanic languages prior to the 15th century, which is now known as 120, one hundred and twenty, or six score. The number was simply described as hundred and translated into Latin in Germanic-speaking countries as centum (Roman numeral C), but the qualifier "long" is now added because present English uses the word "hundred" exclusively to refer to the number of five score (100) instead.
The long hundred was 120 but the long thousand was reckoned decimally as 10 long hundreds (1200).
- "Long Hundred" | 2021-02-08 | 97 Upvotes 106 Comments
The obsolete units of measurement of German-speaking countries consist of a variety of units, with varying local standard definitions. Some of these units are still used in everyday speech and even in stores and on street markets as shorthand for similar amounts in the metric system. For example, some customers ask for one pound (ein Pfund) of something when they want 500 grams.
The metric system became compulsory on 1 January 1872, in Germany and on 1 January 1876, in Austria.
Some obsolete German units have names similar to units that were traditionally used in other countries, and that are still used in the United Kingdom (imperial units) and the United States (United States customary units).
- "Obsolete German Units of Measurement" | 2021-04-11 | 84 Upvotes 105 Comments
In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are parts-per-million (ppm, 10−6), parts-per-billion (ppb, 10−9), parts-per-trillion (ppt, 10−12) and parts-per-quadrillion (ppq, 10−15). This notation is not part of the International System of Units (SI) system and its meaning is ambiguous.
- "Uno – The “Unit” for Dimensionless Quantities" | 2021-07-01 | 131 Upvotes 115 Comments
Yan Tan Tethera or yan-tan-tethera is a sheep-counting system traditionally used by shepherds in Northern England and some other parts of Britain. The words are numbers taken from Brythonic Celtic languages such as Cumbric which had died out in most of Northern England by the sixth century, but they were commonly used for sheep counting and counting stitches in knitting until the Industrial Revolution, especially in the fells of the Lake District. Though most of these number systems fell out of use by the turn of the twentieth century, some are still in use.
- "Yan tan tethera: A Celtic sheep-counting system" | 2022-01-09 | 12 Upvotes 2 Comments
Many people have made use of, or invented, units of measurement intended primarily for their humor value. This is a list of such units invented by sources that are notable for reasons other than having made the unit itself, and that are widely known in the anglophone world for their humor value.
- "List of Humorous Units of Measurement" | 2022-11-04 | 12 Upvotes 3 Comments
A thousandth of an inch is a derived unit of length in a system of units using inches. Equal to 1⁄1000 of an inch, a thousandth is commonly called a thou (used for both singular and plural) or particularly in North America a mil (plural mils).
The words are shortened forms of the English and Latin words for "thousand" (mille in Latin). In international engineering contexts, confusion can arise because mil is a formal unit name in North America but mil or mill is also a common colloquial clipped form of millimetre. The units are considerably different: a millimetre is approximately 39 mils.
- "Thousandth of an Inch" | 2023-02-21 | 35 Upvotes 65 Comments