Source: https://guthlabs.ai/docs/instruments/tip-calculator/

instrument / verified-clean

# Tip Calculator

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/tip-calculator/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/tip-calculator/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/tip-calculator/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/tip-calculator/qualification/>)

## Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

**Area**: Finance, Economics & Business (educational only — never individualized investment, tax, or legal advice)

**Tranche**: tranche-5

**Evidence ID**: t5-112

**Ledger rows**: 1

No ledger note is attached.

## Review findings

The core tip and total arithmetic is standard under the stated unit assumptions, but the specification is incomplete for round-up and tip-per-person behavior. Retain the educational-only disclaimer and avoid presenting the calculated percentage as a required or personalized tipping recommendation.

### Formula and scope findings

- The tip formula is correct only if tip% is supplied as a whole percentage and converted by dividing by 100; the specification does not define whether 20 means 20% or 0.20.

- The round-up option has no formula or definition: it is unclear whether it rounds the tip, total, or per-person amount, and to what currency increment.

- The claimed tip-per-person output has no formula and the required split-count input is missing from the input specification.

- Currency rounding is unspecified, especially when the tip or per-person amount has fractional cents.

### Unit assumptions

- bill amount is a nonnegative amount in a single currency, expressed in major currency units such as dollars.

- tip% is a percentage expressed as a whole number, so 20 means 20% and is converted as 20/100 = 0.20.

- tip and total use the same currency as the bill.

- For these test vectors, round_up=false means no additional rounding is applied.

- tip per person is assumed to be tip divided by a positive split_count; this assumption is not defined in the specification.

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

A split count of zero produces an undefined tip-per-person result and must be rejected. The round-up branch is also not fully defined by the specification because it does not state whether rounding applies to the total, tip, or another currency increment.

## Errata and corrections

No applied erratum is attached to this unique-name record.

## Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

````
{
  "inputs": {
    "bill_amount": 27.8,
    "tip_percent": 20,
    "round_up": false,
    "split_count": 2
  },
  "expected_outputs": {
    "tip": 5.56,
    "total": 33.36,
    "tip_per_person": 2.78
  },
  "working": "Convert 20% to 0.20. Tip = 27.80 × 0.20 = 5.56. Total = 27.80 + 5.56 = 33.36. Tip per person = 5.56 ÷ 2 = 2.78."
}
````

## Related workflows

No source-defined multi-instrument workflow membership is recorded.

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`

- `evidence-tranche5/tranche5-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`