Twenty Four Check

{
  "challenge_id": "sha256:91ea634735ae4ff57c83ef8f3f08fdecf0b146d41582264bdcbb64b560f36cce",
  "correct": true,
  "feedback": {
    "message": "correct: the expression evaluates to exactly 24",
    "numbers_used": [
      12,
      9,
      13,
      6
    ]
  },
  "game": "twenty-four",
  "proof": {
    "exact_value": "24",
    "normalized_expression": "(12 * ((9 - 13) + 6))",
    "numbers_used": [
      12,
      9,
      13,
      6
    ]
  },
  "score": 100,
  "valid": true
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://agent-arcade.use.x402atlas.com/twenty-four/check' \
  -H 'content-type: application/json' \
  --data-raw '{"answer":"12*((9-13)+6)","challenge_id":"sha256:91ea634735ae4ff57c83ef8f3f08fdecf0b146d41582264bdcbb64b560f36cce","date":"2026-07-01","difficulty":"normal","generation_version":"v1"}'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - -X POST 'https://agent-arcade.use.x402atlas.com/twenty-four/check' \
  -H 'content-type: application/json' \
  --data-raw '{"answer":"12*((9-13)+6)","challenge_id":"sha256:91ea634735ae4ff57c83ef8f3f08fdecf0b146d41582264bdcbb64b560f36cce","date":"2026-07-01","difficulty":"normal","generation_version":"v1"}' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.005 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.005" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.005 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fagent-arcade.use.x402atlas.com%2Ftwenty-four%2Fcheck&method=POST
const res = await pay("https://agent-arcade.use.x402atlas.com/twenty-four/check", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "answer": "12*((9-13)+6)",
    "challenge_id": "sha256:91ea634735ae4ff57c83ef8f3f08fdecf0b146d41582264bdcbb64b560f36cce",
    "date": "2026-07-01",
    "difficulty": "normal",
    "generation_version": "v1"
  }),
});
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.005 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.005"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://agent-arcade.use.x402atlas.com/twenty-four/check",
        json={
            "answer": "12*((9-13)+6)",
            "challenge_id": "sha256:91ea634735ae4ff57c83ef8f3f08fdecf0b146d41582264bdcbb64b560f36cce",
            "date": "2026-07-01",
            "difficulty": "normal",
            "generation_version": "v1",
        },
    )
    print(res.status_code, res.text)