CAS：78-93-3

CAS：108-94-1

CAS：67-64-1

CAS：64-19-7

CAS：141-78-6

CAS：108-88-3

CAS：71-43-2

CAS：64-17-5

CAS：67-56-1

### 2 - Wikipedia

In pre-1972 Indonesian and Malay orthography, 2 was shorthand for the redupliion that forms plurals: orang (person), orang-orang or orang2 (people).[citation needed] In Astrology, Taurus is the second sign of the Zodiac.For Pythagorean numerology (a pseudoscience) the nuer 2 represents duality, the positive and negative poles that come into balance and seek harmony.

Evolution In mathematics List of basic calculations In science In sports

### 2 - Wiktionary

2022125 2 ( prev 1, next 3 ) The cardinal nuer two. A digit in the decimal system of nuering, as well as octal, and hexadecimal. A rotational symmetry element in the Hermann-Mauguin notation, indiing a rotation over π (twofold axis). ( mathematics) The two-element Boolean algebra, two-point discrete space or a ( canonical) two-element set.

### 2 (nore) Wikipédia

2 est un nore premier palindrome et permutable. 2 est l''un des 15 nores premiers super-singuliers. 2 est le plus petit nore premier non brésilien. 2 est le 4e nore de Fibonacci, noté F 4 (c''est donc un nore premier de Fibonacci) 2 est le 1er nore de Lucas, noté L 0. 2 est le 3e nore de Pell.

### Pythonnumpy：print(a[0::2])、a[::2]、[:,2]、[1:,-1:] …

2019921 numpy [ ] , python 0 -1 ： start:stop:step ：

### _

Beijing No.2 Middle School 1724 (2003) () “”“、、、”

、、“”“”. “”2“”“”

### Square root of 2 - Wikipedia

The square root of 2 (approximately 1.4142) is a positive real nuer that, when multiplied by itself, equals the nuer 2.It may be written in mathematics as or /, and is an algebraic nuer.Technically, it should be called the principal square root of 2, to distinguish it from the negative nuer with the same property.

History Decimal value Proofs of irrationality Multipliive inverse