tuhannesosa

Tuhannesosa is a term used in Estonian mathematics and measurements to denote one thousandth of a quantity. It represents the scalar factor 1/1000, so taking a tuhannesosa of a number x means multiplying x by 0.001, i.e., x/1000. As a decimal, the unit is 0.001, and as a percentage it is 0.1 percent. The concept is the Estonian equivalent of the SI prefix milli- (10^-3) and of the idea of one per mille (1‰) when applied to a unit.

Etymology and use: the word is formed from the roots for “thousand” (tuhat) and “part” or “portion” (osa). It is used in everyday language and in some mathematical explanations to describe small fractions of a whole, particularly in contexts such as measurements, proportions, and quantities where a very small portion is relevant.

Notation and examples: the basic rule is that a tuhannesosa of x equals x/1000. For example, one tuhannesosa of 2 is 0.002, one tuhannesosa of 1200 is 1.2, and one tuhannesosa of 400 is 0.4. This unit is especially useful for expressing precise fractions without switching to fractions or higher-precision decimals.

Relation to other terms: tuhannesosa corresponds to the familiar fraction 1/1000 and to the decimal 0.001. In practical terms, it is equivalent to one per mille when discussing portions of a unit, such as 1 tuhannesosa of a liter being 0.001 liters.