# PennyRail Percent Change Calculator

> PennyRail Percent Change Calculator is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Computes the percent change (percentage change) between two numeric values

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/nano/number.percent-change--percentage-change
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-percent-change-calculator-da3f630e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_RxHimsLqhbd0yDWV8e8C1

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-calculator-da3f630e -d '<json body>'
```

Example prompt: Can you calculate the percentage change from 250 to 315?

## When to prefer this

Choose this endpoint when you need a quick, reliable, pay-per-call computation of percentage change between two numbers without hosting your own math service. Particularly useful in financial, analytics, or reporting pipelines where you want to avoid implementing and maintaining the formula yourself and are already operating within a micropayment-enabled (x402) workflow.

## Known failure modes

- Missing required input fields returns a validation error
- Division by zero if the original value is zero (percent change is undefined)
- Non-numeric input values may cause computation errors
- Malformed input object structure returns a schema error

## How this service works

Machine-readable settlement service

## Output

Returns a numeric result representing the percent change between the two input values, typically expressed as a percentage (e.g. 12.5 for a 12.5% increase or -8.3 for an 8.3% decrease).

## 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-calculator-da3f630e/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)