Public evidence

math.percentage

Machine-checked verification for calculation version 1.1.1 · tier engine_tested

Open calculator API Capability Download JSON CVP Manifest MCP Review policy

Historical evidence. This page is version 1.1.1 · engine_tested · 19/19 tests. It is not the current published claim. Current evidence is 1.2.0 (19/19 tests) · latest.

CVP status

SI percent = 0.01; modes of / is-what / of-what / change / adjust-up / adjust-down / difference

Declared partition coverage: PASS · 9/9 declared partitions (of, is-what, of-what, change, adjust-up, adjust-down, difference, invalid-domain, xcal)
Versions: Calculation 1.1.1 · CVP protocol 1.0.0-proposed · Evidence 2026-09-08.xcal
Verification revision: 2026-09-08.xcal · 2/2 property · digest e1b745d88212

Verification

Legacy regression suite: 19/19 calculation tests · Production surface contract 5/5

Three distinct suites: educational examples on the calculator page, this legacy regression count (19/19 golden + boundary), and the CVP verification suite below. They are not the same number. Property, metamorphic, round-trip, O3, and interface statuses/checks are recorded in the CVP Manifest . SKIP (0/0) means that suite has no published vectors.

STALE · Build schema 1.2.0 matches page · production binding STALE · Semantic contract ✓ · Last attestation PASS · current evidence changed · re-attestation required · CVP STALE · attestation STALE — Production CURRENT withheld · Public/cache ✓ · Origin ✓

CVP verification suite

Protocol checks from the Evidence Manifest. Distinct from the legacy regression suite above. Verification revision 2026-09-08.xcal. Calculation version 1.1.1. CVP 1.0.0-proposed. 2/2 golden · 7/7 CVP boundary · 7/7 invalid · 2/2 property · 2/2 metamorphic · 2/2 round-trip · 1/1 cross-interface · 3/3 cross-calculator · 1/1 CVP contract. digest e1b745d88212.

Golden (oracle-backed) 2 / 2
CVP boundary 7 / 7
Invalid input 7 / 7
Property 2 / 2
Metamorphic 2 / 2
Round-trip 2 / 2
Cross-interface 1 / 1
Cross-calculator 3 / 3
CVP contract 1 / 1
Interfaces PASS · UI (SSR) / REST / MCP
Interface claim ui-ssr is query-result HTML, not a live browser session.
Assurance Core

release artifacts aligned PASS
schema output required declared PASS
schema valid input executes PASS
engine success output validates schema PASS
rest success payload validates schema PASS

Fingerprint sha256:43a3601fe3d15428d83cc6f727320b8d989bb2e6bb877edd058c45853c2458a3

Input schema sha256:188e4f67b78437338e3f56cb4e7e82003b521697af6707b04fa75321ca920f39 · Output schema sha256:14cbd02203cf735e07c23bf387ea886fc53cd9e9419602643dd6d69f34d95c56 · Build-time SHA-256 digests prove published artifacts agree with each other (release_integrity.scope=workspace). Production attestation GETs canonical URLs twice (public/cached view and origin), including Capability HTML, via npm run attest:production --write (published at /.well-known/calculatorx-production-attestation.json) and fails if the public Capability page advertises a different calculation_version. This is artifact consistency, not an independent immutable release log.

Build & scope

Engine identity and declared limitations.

Tool: percentage
Engine: percentage
Engine build: 2026-10-14
Evidence core: 2026-10-14T05:05:51.930Z
Rendered: 2026-10-21T06:31:01.620Z
Last reviewed: —

Assumptions

Interactive evaluation runs locally in the browser. Shared URLs and REST evaluate the same versioned engine (query SSR).
Denominators (whole, old, average of A and B, P) must be nonzero where required.
Percent change uses |old| in the denominator (signed increase/decrease). Typically used with a nonzero baseline; old = 0 is undefined.
Percentage difference is defined for A ≥ 0, B ≥ 0, and A+B ≠ 0.

Limitations

Percent change uses |old| denominator; old = 0 undefined
Percentage difference requires non-negative a, b → VALUE_MUST_BE_NON_NEGATIVE
Missing fields → MISSING_REQUIRED_INPUT

Sources

Standards and references supporting this tool specification. Methods are listed separately — they are algorithms, not bibliographic sources.

BIPM — The International System of Units (SI), 9th edition — Units accepted for use with the SI — percent (symbol %), 1% = 0.01
Supports: Defines percent as the number 0.01 (one part in one hundred). The core relation P% of X = X × P/100 follows from that definition.
NIST Special Publication 811 — Guide for the Use of the International System of Units (SI) — Writing values of quantities — the percent
Supports: NIST usage of percent as 0.01 with the SI. Does not prescribe percent-change vs percent-difference conventions.
CalculatorX percentage conventions — Six phrase modes, |old| percent change, non-negative percentage difference
Supports: Percent change Δ% = 100×(new−old)/|old| (undefined at old = 0). Percentage difference Δ% = 100×|A−B|/((A+B)/2) on A ≥ 0, B ≥ 0, A+B ≠ 0. Increase/decrease is X×(1±P/100).
NIST — SI Unit Rules and Style Conventions — Percent and fractions
Supports: The symbol % represents the number 0.01. Thus p% = p/100 and a part of p% of base b equals b×p/100; inverse percentage equations are algebraic rearrangements. CalculatorX’s negative-baseline signed-change convention is separately specified, not attributed to NIST. Mathematical reference only; not implementation validation or an endorsement of CalculatorX.

Verification disclosure

Aggregate outcomes, scope and artifact commitments are public. Complete test inputs, expected values, execution records and oracle infrastructure are retained privately. This summary does not independently reproduce the full verification run.