# 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 (count, mean, min, max, etc.) over an array of numbers via a micropayment-gated API

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/nano/number.stats--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-1d67b906
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bpiymPqx5gjMokyiU3CEm

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-1d67b906 -d '<json body>'
```

Example prompt: Can you calculate 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 a quick, pay-per-use descriptive statistics computation over a numeric array without spinning up your own statistical library or service. It is well-suited for lightweight, one-off analyses in agent workflows where installing a math library is impractical and the $0.001 micropayment cost per call is acceptable.

## Known failure modes

- Empty array input may return an error or undefined statistics
- Non-numeric values in the array may cause a computation error
- Malformed input (non-array type) returns a validation error
- Payment failure (insufficient USDC balance) results in a 402 response and no computation
- Very large arrays may time out on the serverless Vercel infrastructure

## How this service works

Machine-readable settlement service

## Output

A JSON object containing descriptive statistics computed over the input number array, likely including count, sum, mean, median, min, max, variance, and standard deviation.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pennyrail-number-stats-1d67b906/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)