∑ English name: Sigma Chinese name: sigma (capital σ, lowercase σ), the 18th Greek letter.

in Greek, if the last letter of a word is lowercase sigma, what should I write that letter as? This letter is also called final sigma(Unicode: U+3C2). In modern Greece, the number stands for 6.

in mathematics, we use it as a summation symbol.

management method, one sigma equals one in a million. In production, six sigma (3.4 parts per million in mathematical calculation and 6 parts per million in management) is used to represent the normal defective products that millions of products can have.

Sigma trademark: Sigma σ 5-26℃. THE TEMPERATURE IS HEIGHT, 26℃- creating the history of the highest temperature in oxidizing atmosphere, Sigma Machao high temperature electric furnace, Sigma ultra-high temperature laboratory.