Protsent

Protsent, or percent, is a way to express a number as a fraction of one hundred. It is written with the symbol % and read as “per cent.” By definition, x% equals x divided by 100.

In practice, percentages are used to describe portions, rates, and changes. To convert a percentage to a decimal, multiply by 0.01; to express it as a fraction, x% equals x/100. For example, 25% of 240 is 60; 0.25 is equivalent to 25/100.

Percentage changes compare two values. The percent change from a to b is (b − a) / a × 100%. For instance, a price rising from 50 to 60 represents a 20% increase.

Important caveats: a percentage depends on a base value, so comparing percentages with different bases can be misleading. Rounding can obscure small differences, and the distinction between percentage points and percent is a common source of error.

Historically, the term comes from Latin per centum, meaning by the hundred. The percent sign % developed in Europe in the early modern period and became widely adopted in mathematics and commerce.

Related concepts include permille (‰), which denotes per thousand, and basis points in finance, used to describe small changes in interest rates. The percent is a standard tool in statistics, economics, science, and everyday life for expressing relative quantities.