{"uid":"cap_SarNRJVfYn2VRBHooE3xR","slug":"agent-arcade-twenty-four-puzzle-answer-checker-d088efd2","name":"Agent Arcade: Twenty-Four Puzzle Answer Checker","description":"Twenty-Four answer check — verifies a 24-game arithmetic expression with exact rational math against the deterministic daily challenge.","url":"https://agent-arcade.use.x402atlas.com/twenty-four/check","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"date":{"type":"string","format":"date","pattern":"^\\d{4}-\\d{2}-\\d{2}$","description":"UTC challenge date (YYYY-MM-DD)"},"answer":{"type":"string","maxLength":256,"description":"Twenty-Four arithmetic expression using each supplied number exactly once with + - * / and parentheses, evaluating to exactly 24"},"difficulty":{"enum":["normal"],"type":"string","description":"Challenge difficulty"},"challenge_id":{"type":"string","pattern":"^sha256:[0-9a-f]{64}$","description":"The challenge_id from the daily envelope (sha256:...)"},"generation_version":{"enum":["v1"],"type":"string","description":"Pinned generator version of the referenced challenge"}}},"responseSchema":{"type":"json","example":{"game":"twenty-four","proof":{"exact_value":"24","numbers_used":[12,9,13,6],"normalized_expression":"(12 * ((9 - 13) + 6))"},"score":100,"valid":true,"correct":true,"feedback":{"message":"correct: the expression evaluates to exactly 24","numbers_used":[12,9,13,6]},"challenge_id":"sha256:91ea634735ae4ff57c83ef8f3f08fdecf0b146d41582264bdcbb64b560f36cce"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.005","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_Ymk219vK3qmCer5xj_58U","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Validates a mathematical expression using exactly four given numbers to check whether it correctly evaluates to 24","exampleAgentPrompt":"Can you check if my solution to the 24 puzzle is correct? I was given the numbers 12, 9, 13, and 6, and my expression is (12 * ((9 - 13) + 6)) — does it equal 24 using all four numbers?","exampleUseCases":[{"title":"AI agent self-evaluation on puzzle","prompt":"I need to verify my agent's answer to the twenty-four game: it was given numbers 3, 8, 3, 8 and proposed the expression (8 / (3 - 8/3)) — can you check if that's a correct and valid solution?"},{"title":"Tutoring app answer feedback","prompt":"A student submitted (4 + 2) * (9 - 5) as their answer to a 24 puzzle using the numbers 4, 2, 9, and 5 — can you validate whether that's correct and give feedback?"},{"title":"Competitive leaderboard score submission","prompt":"Submit and score my twenty-four puzzle solution: my numbers were 1, 5, 5, 5 and my expression is 5 * (5 - 1/5) — please check it and return my score."}],"resultDescription":"Returns a JSON object indicating whether the expression is valid (syntactically correct and uses the exact four provided numbers), whether it is correct (evaluates to exactly 24), a numeric score (0–100), a proof object detailing the exact value, numbers used, and normalized expression, a feedback message explaining the result, and the challenge_id hash.","failureModes":["Expression uses wrong numbers or fewer/more than four — returns valid:false","Expression does not evaluate to 24 — returns correct:false with score 0","Malformed or unparseable expression — returns validation error","Missing required fields in request body — 400 Bad Request","Payment not provided — returns HTTP 402 challenge requiring X-PAYMENT header","Network or server error — 5xx response"],"whenToPreferThis":"Choose this endpoint when you need to programmatically verify a user's or agent's arithmetic expression as a valid solution to the Twenty-Four puzzle game — especially in AI agent benchmarking, educational math apps, or competitive puzzle platforms. It is the authoritative checker for the /twenty-four game on the Agent Arcade platform and returns structured proof and scoring data suitable for leaderboards or automated feedback loops.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T00:38:23.686Z","isFirstParty":false}