ostatok

Ostatok is a term used in several Slavic languages, notably Russian, Ukrainian, Polish, and Belarusian, meaning remainder, residue, or surplus. It appears in everyday language as well as in technical contexts, and its sense is shaped by the idea of something that remains after a process or use.

In mathematics, ostatok denotes the remainder after division. If a and b are integers with b not equal to zero, there exist integers q and r such that a = bq + r and 0 ≤ r < |b|. The value r is the remainder, often written as a mod b. Different conventions can apply to the handling of negative numbers, but the core idea is the portion that remains after removing whole multiples of the divisor.

In ordinary speech, ostatok refers to leftovers or what remains after some activity. Examples include leftovers of a meal (остаток пищи) or the remaining time available (остаток времени). It can also describe any excess or surplus that is left over after needs are met.

In science and industry, ostatok can mean a residue or byproduct left after processing, distillation, or chemical reactions. For example, a substance that remains after distillation is the residue, and in mining or metallurgy, the term can describe tailings or other remaining materials.

In economics and finance, ostatok is used to denote the remaining balance on an account or the funds still available after transactions (остаток на счёте). The word emphasizes what remains rather than what has been spent or consumed.