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Math & AlgebraGenerated accuracy model review: 2026-05-06
Percentage Calculator accuracy and testing
This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.
Formula source
- The math depends on the mode: 1. **X% of Y**: (X / 100) * Y 2. **X is what % of Y**: (X / Y) * 100 3. **Percentage Change**: ((New - Old) / Old) * 100
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Mode: What is X% of Y?
- Value A (X): 20
- Value B (Y): 100
Expected outputs
- Percentage Result: 20
- Explanation: 20% of 100
Known limitations
- This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
- Use the result as a planning estimate unless the calculator page states a stricter purpose.
Assumptions
- Percentage change uses the first value as the starting point and the second value as the new value.
- Percent-of mode returns the raw percentage and shows a one-decimal explanation.
- Percentage change results are rounded to two decimal places for display.
Unit handling
- Mode accepts one of the configured options.
- Value A (X) accepts numeric values.
- Value B (Y) accepts numeric values.
Rounding rules
- Number displays use up to 2 decimal places in the calculator UI.
Version history
1.0.0 - 2026-05-06
Generated accuracy and testing page from the current percentage-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Percentage Calculator.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.