Aninteger is determined to beeven if it isdivisible by two. When written in base 10, allmultiples of 2 will end in0, 2, 4, 6, or8;[5] more generally, in any even base, even numbers will end with an even digit.
Two is most commonly adeterminer used withplural countable nouns, as intwo days orI'll take these two.[10]Two is anoun when it refers to the number two as intwo plus two is four.
The wordtwo is derived from theOld English wordstwā (feminine),tū (neuter), andtwēġen (masculine, which survives today in the formtwain).[11]
Evolution of the Arabic digit
The digit used in the modern Western world to represent the number 2 traces its roots back to the IndicBrahmic script, where "2" was written as two horizontal lines. The modernChinese andJapanese languages (and KoreanHanja) still use this method. TheGupta script rotated the two lines 45 degrees, making them diagonal. The top line was sometimes also shortened and had its bottom end curve towards the center of the bottom line. In theNagari script, the top line was written more like a curve connecting to the bottom line. In the ArabicGhubar writing, the bottom line was completely vertical, and the digit looked like a dotless closing question mark. Restoring the bottom line to its original horizontal position, but keeping the top line as a curve that connects to the bottom line leads to our modern digit.[12]
In science
The firstmagic number - number of electrons in the innermost electron shell of an atom.[13]
^Wilson, Robin (2014).Four Colors Suffice (Revised color ed.). Princeton University Press.ISBN978-0-691-15822-8.
^Carrell, Jim. "Chapter 1 | Euclidean Spaces and Their Geometry".MATH 307 Applied Linear Algebra(PDF).Archived(PDF) from the original on 2024-06-05. Retrieved2024-06-05.
^Georges Ifrah,The Universal History of Numbers: From Prehistory to the Invention of the Computer transl. David Bellos et al. London: The Harvill Press (1998): 393, Fig. 24.62
