Units questions

Avogadro's number, number of units in one mole of any substance (defined as its molecular weight in grams), equal to 6.022140857 × 1023. The units may be electrons, atoms, ions, or molecules, depending on the nature of the substance and the character of the reaction.

The yard is an English unit of length, in both the British imperial and US customary systems of measurement, that comprises 3 feet or 36 inches. It is by international agreement in 1959 standardized as exactly 0.9144 meters.

A furlong is a measure of distance in imperial units equal to one-eighth of a mile, equivalent to 660 feet, 220 yards, 40 rods, or 10 chains. It has very limited use, with the notable exception of horse racing in most English-speaking countries, including the United Kingdom, Ireland, Canada, and the United States. Furlongs are also used in conjunction with miles to indicate distances on highway signs in Myanmar.

The barrel is one of several units of volume applied in various contexts; there are dry barrels, fluid barrels, oil barrels and so on. The volumes in common usage range from about 100 to 200 litres. In the worldwide oil industry, an oil barrel is defined as 42 US gallons, which is about 159 litres or 35 imperial gallons.

The Bortle scale is a nine-level numeric scale that measures the night sky's brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution. It was created by John E. Bortle in 2001.

The International Bittering Units scale, or simply IBU scale, is used to approximately quantify the bitterness of beer. This scale is not measured on the perceived bitterness of the beer, but rather the amount of iso-alpha acids.

The International System of Units (abbreviated as SI) is the modern form of the metric system, and is the most widely used system of measurement. It comprises a coherent system of units of measurement built on seven base units (ampere, kelvin, second, metre, kilogram, candela, mole) and a set of twenty decimal prefixes to the unit names and unit symbols.

In computing, the mega prefix usually means the number 1 048 576 and is the result of 1024 × 1024 = 2 ^ 20. In decimal units it is slightly different, but they are not used in informatics.1 MB = 1024 kB 1 kB = 1024 B 1 MB = 1 048 576 B 1 B = 8 b (bits) 1 MB = 8 388 608 b

President Gerald Ford signed the Metric Conversion Act in1975. It declared the metric system "the preferred system of weights and measures for United States trade and commerce", but permitted the use of United States customary units in all activities. The metrification board was abolished in 1982 by President Ronald Reagan.

Common data rate units are multiples of bits per second (bit/s) and bytes per second (B/s). For example, the data rates of modern residential high-speed Internet connections are commonly expressed in megabits per second (Mbit/s).