Stigma (letter) Stigma (letter) Stigma (ϛ) is a ligature of the Greek letters sigma (Σ) and tau (Τ), which was used in writing Greek between the Middle Ages and the 19th century. It is also used as a numeral symbol for the number 6. In this unrelated function, it is a continuation of the old letter digamma (originally Ϝ, cursive form ), which had served as a numeral since antiquity and was conflated with the σ-τ ligature in the minuscule handwriting of the Middle Ages. The στ ligature (, ) was one of many ligature forms that came into widespread use as
Metrication in the United States SI is widespread for many applications. Residential electric power plans use kilowatt hours. The luminous flux from lamps is specified in lumens rather than candlepower. The letter "K" is commonly used to denote "thousand" (e.g., "She earns $80K"), even though this is inconsistent with the lowercase "k" in SI. This usage has largely replaced the letter "G" (for "grand", used almost exclusively for money) and the Roman numeral "M" that was commonly used for "thousand" before the 1960s; in fact, the "M" has now come to denote "million" (e.g., "$32.5M budget"). Televised and radio weather reports are given in degrees