numberformatting

Number formatting refers to the conventions used to present numerical values to readers and to parse user input. It encompasses digit symbols, decimal separators, thousands separators, and the choice of notation and precision. Formats vary by locale and context, affecting readability and interpretation.

Common elements include decimal separators (for example, a period in many English-speaking locales and a comma in many European locales), thousands separators for digit grouping, currency symbols, percentage signs, and units. Formats also encode rounding and significant figures, choose fixed or scientific notation, and may pad numbers for alignment. Negative numbers may be shown with a leading minus sign or enclosed in parentheses.

Locale-specific rules are encoded in standards and libraries such as the Unicode Common Locale Data Repository (CLDR) and ICU. Programming languages expose formatting facilities, e.g., Intl.NumberFormat in JavaScript, NumberFormat in Java, and format specifications in Python. Data interchange often requires explicit formatting schemas to ensure consistent presentation across systems.

Examples illustrate differences: 1234.56 in en-US versus 1 234,56 in many European locales; or price formatting as $1,234.56 or €1.234,56 depending on locale and currency conventions. Challenges include inconsistent symbol placement, space usage, and bidirectional text in multilingual contexts.