Source: https://guthlabs.ai/docs/instruments/future-value-lump-sum/

instrument / verified-clean

# Future Value (Lump Sum)

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/future-value-lump-sum/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/future-value-lump-sum/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/future-value-lump-sum/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/future-value-lump-sum/qualification/>)

## Ledger state

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

**Area**: Finance, Economics & Business

**Tranche**: calibration-1

**Evidence ID**: offline/source boundary

**Ledger rows**: 1

No ledger note is attached.

## Review findings

The lump-sum future-value formula is correct under the stated unit assumptions. Verdict is NEEDS_REVIEW because the exact ambiguity is the undefined formula and sampling convention for the advertised growth curve, plus the absent definition of total growth. The honest label appropriately identifies the educational nature and omission of taxes and fees.

### Formula and scope findings

- The core formula FV=PV(1+r/n)^(nt) is standard for a nominal annual interest rate r compounded n times per year, with t measured in years.

- The specification does not define a formula or representation for total growth; the usual definition is total growth=FV-PV.

- The specification does not define the sampling interval, time points, or formula used for the growth curve, so that output cannot be verified unambiguously.

### Unit assumptions

- r must be supplied as a decimal fraction, such as 0.05 for 5% per year, not as the number 5.

- r is assumed to be a nominal annual rate.

- n is assumed to be a positive integer with units of compounding periods per year.

- t is measured in years; therefore nt is the total number of compounding periods.

- PV and FV must use the same currency units.

- The test-vector total_growth value is defined as FV-PV.

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

The n=0 vector produces an undefined division by zero. The instrument should reject n=0 before evaluating the formula; accepting it would create an undefined result or implementation-dependent behavior.

## 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": {
    "PV": 1000,
    "r": 0.08,
    "n": 4,
    "t": 2
  },
  "expected_outputs": {
    "FV": 1171.659381004512,
    "total_growth": 171.659381004512
  },
  "working": "Periodic rate = r/n = 0.08/4 = 0.02. Total periods = n*t = 4*2 = 8. Growth factor = (1+0.02)^8 = 1.02^8 = 1.171659381004512. FV = 1000*1.171659381004512 = 1171.659381004512. Total growth = FV-PV = 1171.659381004512-1000 = 171.659381004512."
}
````

## 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-tranche2/batch10-output.jsonl`

- `BOUNDARY_HAZARD_CATALOG.json`