Expected Value

{
  "asOf": "2026-10-11T14:44:17.888Z",
  "bestOutcome": {
    "payoff": 35,
    "probability": 0.02631578947368421
  },
  "breakEvenCost": -0.052631578947368474,
  "costApplied": 0,
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "expectedValue": -0.052631578947368474,
  "notChecked": [
    "utility or risk preference: a positive expected value does not make a bet advisable (Kelly, ruin and variance matter)",
    "the accuracy of the probabilities you supplied",
    "…1 more"
  ],
  "outcomes": [
    {
      "payoff": 35,
      "probability": 0.02631578947368421
    },
    {
      "payoff": -1,
      "probability": 0.9736842105263158
    }
  ],
  "probabilityLoss": 0.9736842105263158,
  "probabilityPositive": 0.02631578947368421,
  "reasons": [
    "EV = sum of payoff x probability; variance = sum of (payoff - EV)^2 x probability.",
    "Over many plays you lose about 0.0526 per play on average; short runs can still win."
  ],
  "source": "computed locally",
  "standardDeviation": 5.762617133966734,
  "summary": "Expected value -0.052632 per play; standard deviation 5.7626; chance of a positive result 2.63%.",
  "variance": 33.20775623268698,
  "verdict": "NEGATIVE_EXPECTATION",
  "worstOutcome": {
    "payoff": -1,
    "probability": 0.9736842105263158
  }
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://probability-calc.x402tookit.com/expected-value?normalize=true&outcomes=35%3A1%2C-1%3A37'

# 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 - 'https://probability-calc.x402tookit.com/expected-value?normalize=true&outcomes=35%3A1%2C-1%3A37' \
  | 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 $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
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 $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fprobability-calc.x402tookit.com%2Fexpected-value
const res = await pay("https://probability-calc.x402tookit.com/expected-value?normalize=true&outcomes=35%3A1%2C-1%3A37");
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 $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://probability-calc.x402tookit.com/expected-value?normalize=true&outcomes=35%3A1%2C-1%3A37")
    print(res.status_code, res.text)