Desimal

Desimal, or decimal, refers to the base-10 positional numeral system used to represent real numbers. A decimal number consists of an integer part and a fractional part separated by a decimal point in most contexts, or by a decimal comma in many European countries. The digits 0 through 9 assign place values from left to right in powers of ten (10^2, 10^1, 10^0) and, to the right of the decimal point, in negative powers of ten (10^-1, 10^-2, etc.). The term desimal/decimal derives from Latin decimalis, meaning tenth.

The system relies on Hindu-Arabic numerals and became standard in Europe after the work of Simon Stevin in the 16th century, who popularized decimal fractions. In decimal notation, numbers may be written as terminating decimals (finite digits after the decimal point) or as repeating decimals (infinite digits with a repeating pattern). For example, 0.5 is terminating, while 0.333... equals 1/3 and is repeating.

Notation can vary by locale: many countries use a decimal point as the separator, while others use a decimal comma. Decimals enable straightforward arithmetic operations—addition, subtraction, multiplication, and division—and are essential for representing measurements, money, and scientific data with a chosen level of precision through rounding or significant figures.

In computing, decimal numbers are often handled using floating-point representations, which can introduce rounding errors due to finite precision. Some applications require exact decimal arithmetic, particularly in financial calculations, prompting the use of specialized decimal or fixed-point formats.