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At about the same time, the Egyptian Rhind Mathematical Papyrus (dated to the Second Intermediate Period, c. 1600 BCE, although stated to be a copy of an older, Middle Kingdom text) implies an approximation of π as 256 ⁄ 81 ≈ 3.16 (accurate to 0.6 percent) by calculating the area of a circle via approximation with the octagon.
f-number. Diagram of decreasing apertures, that is, increasing f-numbers, in one-stop increments; each aperture has half the light-gathering area of the previous one. An f-number is a measure of the light-gathering ability of an optical system such as a camera lens. It is calculated by dividing the system's focal length by the diameter of the ...
Another scale is mass fraction or, equivalently, percent by mass. [2] For example, the abundance of oxygen in pure water can be measured in two ways: the mass fraction is about 89%, because that is the fraction of water's mass which is oxygen. However, the mole fraction is about 33% because only 1 atom of 3 in water, H 2 O, is oxygen.
Molar concentration or molarity is most commonly expressed in units of moles of solute per litre of solution. [1] For use in broader applications, it is defined as amount of substance of solute per unit volume of solution, or per unit volume available to the species, represented by lowercase : [2]
As of 2006, California had an estimated population of 37,172,015, more than 12 percent of the U.S. population. This includes a natural increase since the last census of 1,557,112 people (i.e., 2,781,539 births minus 1,224,427 deaths) and an increase due to net migration of 751,419 people.
An equivalent (symbol: officially equiv; [1] unofficially but often Eq[2]) is the amount of a substance that reacts with (or is equivalent to) an arbitrary amount (typically one mole) of another substance in a given chemical reaction. It is an archaic quantity that was used in chemistry and the biological sciences (see Equivalent weight § In ...
VFAT, a variant of FAT with an extended directory format, was introduced in Windows 95 and Windows NT 3.5. It allowed mixed-case Unicode long filenames (LFNs) in addition to classic 8.3 names by using multiple 32-byte directory entry records for long filenames (in such a way that old 8.3 system software will only recognize one as the valid directory entry).
The table below shows the percentage of free blacks as a percentage of the total black population in various U.S. regions and U.S. states between 1790 and 1860 (the blank areas on the chart below mean that there is no data for those specific regions or states in those specific years). [citation needed]