---
title: "Exact math for agents — the arithmetic LLMs get plausibly wrong"
method: GET
path: "/api/calc"
tags: ["Math"]
---

# Exact math for agents — the arithmetic LLMs get plausibly wrong

`GET /api/calc`

## Request

- Base URL: `https://api.webbersites.com`
- URL: `https://api.webbersites.com/api/calc`
- Auth: API key in header `X-PAYMENT`

Exact math for agents — the arithmetic LLMs get plausibly wrong. Evaluates an expression at 50-significant-digit precision (BigNumber): big-integer multiplication, high-precision division, roots, logs, factorials, unit conversions (12 inch to cm). GET ?expr=…, result returned as an exact string. Deterministic, no AI, never executed as code.

Price: $0.001 per call, paid in USDC via the x402 protocol (see the x402 security scheme).

## Query parameters

- `expr` string, required

## Response `200`

Success

- object
  - `expr` string
  - `result` string: exact result as a string
  - `result_number` number: float64 companion when finite
  - `type` string

## Other responses

- `402`: Payment required — the response body lists accepted payment methods (amount, asset, network, pay-to address). Retry the request with a signed X-PAYMENT header.

---

[API](https://skmtc.dev/webbersites/apis/webbersites-x402-data-api.md) · [All operations](https://skmtc.dev/webbersites/apis/webbersites-x402-data-api/llms.txt) · [OpenAPI document](https://skmtc.dev/webbersites/apis/webbersites-x402-data-api/revisions/c14a76c67a94?raw)