# PennyRail Percent Change / Growth Percent Calculator

> PennyRail Percent Change / Growth Percent Calculator is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.001/call, status down (last checked 2026-11-04).

Computes the percent change (growth percent) between two numeric values via a paid API call

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/nano/number.percent-change--growth-percent?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: down
- Last checked: 2026-11-04
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-percent-change-growth-percent-calculator-686aa293
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZJOoydOIYmg7meRZfYrRn

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability pennyrail-percent-change-growth-percent-calculator-686aa293 -d '<json body>'
```

Example prompt: Calculate the percent change from 200 to 350 for me — I need to know the growth percentage between those two numbers.

## When to prefer this

Choose this endpoint when you need a quick, pay-per-use percent change or growth percent calculation without standing up your own math infrastructure, especially in an agent workflow that already uses x402 micropayment rails and needs a simple numeric transformation step.

## Known failure modes

- Missing or malformed input object returns a validation error
- Non-numeric input values may cause computation failure
- Insufficient USDC balance or failed x402 payment results in 402 Payment Required
- Starting value of zero causes division-by-zero error
- Network timeout on the Vercel serverless function

## How this service works

Machine-readable settlement service

## Output

Returns a numeric percent change (growth percent) value computed from the provided input numbers, packaged as a JSON object with arbitrary additional properties depending on the service's response structure.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "additionalProperties": true
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pennyrail-percent-change-growth-percent-calculator-686aa293/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from pennyrail.vercel.app](https://www.zero.xyz/host/pennyrail.vercel.app/llms.txt)