# PennyRail Number Stats

> PennyRail Number Stats 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 descriptive statistics (e.g. mean, median, min, max, std dev) over an array of numbers

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/f/number.stats
- 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-number-stats-80b001d7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qd8f_9ifaJXYXgtOvUo1_

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-number-stats-80b001d7 -d '<json body>'
```

Example prompt: Can you compute the descriptive statistics — mean, min, max, and standard deviation — for this list of numbers: [4, 7, 13, 2, 19, 8, 5]?

## When to prefer this

Choose this endpoint when you need fast, lightweight descriptive statistics on a numeric array without standing up your own computation infrastructure. It is ideal for agents that process small-to-medium numeric datasets on demand and want a pay-per-call model at $0.001 USDC, avoiding heavier analytics APIs or local code execution.

## Known failure modes

- Empty input array returns an error or undefined result
- Non-numeric values in the array cause a type error or malformed response
- Missing 'input' field in request body returns a 400-level error
- Very large arrays may time out or exceed payload limits
- Payment failure (402) if USDC balance is insufficient

## How this service works

Machine-readable settlement service

## Output

Returns a JSON object with an 'operation' string identifying the statistical operation performed and a 'result' field containing the computed value(s), such as mean, median, min, max, count, sum, or standard deviation. Additional fields may be present depending on the operation.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "operation",
  "result"
 ],
 "properties": {
  "result": {},
  "operation": {
   "type": "string"
  }
 },
 "additionalProperties": true
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pennyrail-number-stats-80b001d7/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)