Decimal
A decimal is a base-ten numeric representation or type with defined precision and rounding semantics for decimal-valued arithmetic.
Build Financial Software with Generative AI (From Scratch)
Decimal is Python's arbitrary-precision decimal arithmetic type for representing base-ten numbers without the usual binary floating-point approximation.
- How it is used
- Preserves ACH debit and credit totals while moving them through parsing, database storage, APIs, and dashboard calculations.
- How deep it goes
- Demonstrates string construction, schema fields, API typing, client conversion, and method-based addition; defers Decimal internals.
- Examples
- Uses ACH file-control debit and credit totals, Decimal('0.1') versus Decimal(0.1), and grouped company batch totals.
- What you can do after
- Apply it by constructing financial values from strings and adding converted debit and credit totals with Decimal methods.
Read how Build Financial Software with Generative AI (From Scratch) explains Decimal →
Grokking Relational Database Design
A DECIMAL data type is an SQL fixed-point numeric type whose precision and scale control the represented number of digits.
- How it is used
- Stores precise values such as product prices and money amounts in SQL table definitions.
- How deep it goes
- Explains precision, scale, fixed-point accuracy, and floating-point rounding risks through database and currency examples.
- Examples
- Uses DECIMAL(5,2) for product prices and contrasts floating-point currency conversion with fixed-point accuracy.
- What you can do after
- Apply it via CREATE TABLE by specifying total and fractional digit limits for accurate numeric columns.
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PostgreSQL Mistakes and How to Avoid Them
NUMERIC is an exact SQL numeric data type for storing values with specified precision and scale.
- How it is used
- Uses exact numeric storage for monetary values and other calculations where floating-point approximation is unacceptable.
- How deep it goes
- Defines NUMERIC and DECIMAL equivalence, explains monetary trade-offs, and warns against cross-database type-name assumptions.
- Examples
- Contrasts NUMERIC with MONEY and floating-point types, then uses Oracle NUMBER migration as a compatibility example.
- What you can do after
- Evaluate numeric choices, select NUMERIC for exact amounts, separate currency, and diagnose migration mappings that risk precision loss.
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ScyllaDB in Action
DECIMAL is a ScyllaDB arbitrary-width decimal data type that represents values precisely.
- How it is used
- Stores precise decimal or very large numeric values when fixed-width or floating-point types are unsuitable.
- How deep it goes
- Defines arbitrary width and precision, contrasts rounding risks, and stops short of detailed storage or arithmetic internals.
- Examples
- Uses monetary values, base-unit integer storage such as cents, and numeric values beyond BIGINT’s range.
- What you can do after
- Evaluate/understand numeric type choices for accuracy, monetary storage, and unusually large values.
Python Workout: 50 ten-minute exercises
Decimal is a Python numeric class that provides decimal floating-point arithmetic with explicitly represented base-ten values.
- How it is used
- Uses Decimal for accurate decimal arithmetic, particularly in financial calculations where float inaccuracies matter.
- How deep it goes
- Demonstrates construction from strings, arithmetic, and conversion to float at the final boundary.
- Examples
- Uses 0.1 plus 0.2, user-entered decimal strings, and a progressively timed taxation calculation.
- What you can do after
- Apply it via Python's Decimal class to perform accurate arithmetic and delay conversion to float.
Read how Python Workout: 50 ten-minute exercises explains Decimal →
Related concepts
- floating-point arithmeticalternative to · Floating-point arithmetic is computation using finite-precision representations of real numbers, which can introduce rounding and range errors.
- number typekind of · A number type is a programming-language or data-system type whose values represent numeric quantities and support defined numerical operations.
- float64contrasts with · Float64 is a 64-bit floating-point numeric type, commonly represented using the IEEE 754 binary64 format.
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