Twenty-Four answer check — verifies a 24-game arithmetic expression with exact r
Twenty-Four answer check — verifies a 24-game arithmetic expression with exact rational math against the deterministic daily challenge.
Answeringour last check, 2026-09-24
1 of 1checks answered this week
635 msmedian answer time
$0.005listed price per call
$0.005price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
POST https://agent-arcade.use.x402atlas.com/twenty-four/check
| Category | Everything else |
|---|---|
| Provider host | agent-arcade.use.x402atlas.com |
| Networks | eip155:137, eip155:42161, eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 8 from 5 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-09-24 | valid payment request | 402 | $0.005 | 635 ms |
Example input (from the provider)
{
"body": {
"answer": "12*((9-13)+6)",
"challenge_id": "sha256:91ea634735ae4ff57c83ef8f3f08fdecf0b146d41582264bdcbb64b560f36cce",
"date": "2026-07-01",
"difficulty": "normal",
"generation_version": "v1"
},
"bodyType": "json",
"method": "POST",
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"additionalProperties": false,
"description": "Twenty-Four answer-check request using the identity from a daily challenge.",
"properties": {
"answer": {
"description": "Twenty-Four arithmetic expression using each supplied number exactly once with + - * / and parentheses, evaluating to exactly 24",
"maxLength": 256,
"type": "string"
},
"challenge_id": {
"description": "The challenge_id from the daily envelope (sha256:...)",
"pattern": "^sha256:[0-9a-f]{64}$",
"type": "string"
},
"date": {
"description": "UTC challenge date (YYYY-MM-DD)",
"format": "date",
"pattern": "^\\d{4}-\\d{2}-\\d{2}$",
"type": "string"
},
"difficulty": {
"description": "Challenge difficulty",
"enum": [
"normal"
],
"type": "string"
},
"generation_version": {
"description": "Pinned generator version of the referenced challenge",
"enum": [
"v1"
],
"type": "string"
}
},
"required": [
"challenge_id",
"generation_version",
"date",
"difficulty",
"answer"
],
"type": "object"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
},
"method": {
"enum": [
"POST"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"additionalProperties": false,
"description": "Twenty-Four answer-check verdict.",
"properties": {
"challenge_id": {
"description": "Canonical ID of the checked challenge",
"type": "string"
},
"correct": {
"description": "The expression solves the challenge (equals 24 exactly)",
"type": "boolean"
},
"feedback": {
"additionalProperties": false,
"description": "Validity feedback; never contains a solution the client did not produce",
"properties": {
"message": {
"type": "string"
},
"numbers_used": {
"items": {
"type": "integer"
},
"type": "array"
}
},
"required": [
"message",
"numbers_used"
],
"type": "object"
},
"game": {
"description": "Twenty-Four game identity.",
"enum": [
"twenty-four"
],
"type": "string"
},
"proof": {
"additionalProperties": false,
"description": "Present only when correct: the client's own verified expression, normalized, with its exact value",
"properties": {
"exact_value": {
"type": "string"
},
"normalized_expression": {
"type": "string"
},
"numbers_used": {
"items": {
"type": "integer"
},
"type": "array"
}
},
"required": [
"normalized_expression",
"exact_value",
"numbers_used"
],
"type": "object"
},
"score": {
"description": "Informational score: 100 correct, 0 otherwise",
"type": "integer"
},
"valid": {
"description": "The expression follows the rules",
"type": "boolean"
}
},
"required": [
"challenge_id",
"game",
"valid",
"correct",
"score",
"feedback"
],
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}