# Crypto Math Check Digits

> Crypto Math Check Digits is a paid API for AI agents from crypto-math.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-31).

Generate or validate Luhn and ISO 7064 mod 97-10 (IBAN-style) check digits for a given numeric or alphanumeric string.

## Facts

- Endpoint: GET https://crypto-math.x402tookit.com/check-digits?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/crypto-math-check-digits-4ae85252
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_e-LDNJ29Gv7fGEGrJrsKL

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability crypto-math-check-digits-4ae85252
```

Example prompt: Can you generate the Luhn check digit for the number 7992739871 — use the Luhn scheme and the generate action?

## When to prefer this

Choose this endpoint when you need deterministic, standards-compliant generation or validation of check digits using Luhn or ISO 7064 mod 97-10 algorithms — including IBAN construction and verification. Prefer it over general-purpose math endpoints when the specific use case involves financial account numbers, credit card numbers, or any identifier that uses these two widely adopted check digit standards.

## Known failure modes

- Missing required 'value' or 'scheme' query parameters returns an error
- Providing letters in a Luhn scheme input (which only accepts digits) causes a validation error
- Invalid country code for IBAN scheme returns an error about unsupported country
- Providing an already-complete number when action=generate may produce incorrect results
- Non-alphanumeric characters in mod97-10 input may cause a parsing error
- Providing a malformed IBAN for validation may return a verdict of invalid with reasons

## How this service works

Generate or validate Luhn and ISO 7064 mod 97-10 (IBAN style) check digits from the string you supply.

## Output

Returns a JSON object containing the computed or validated check digits, the scheme used, a human-readable summary, a verdict (for validation), reasons explaining the result, the IBAN string (if applicable), country code, expected IBAN length, and a disclaimer. For generation, check digits are returned as a string; for validation, a pass/fail verdict with explanatory reasons is provided.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "scheme",
      "value"
     ],
     "properties": {
      "value": {
       "type": "string",
       "description": "luhn: digits; mod97-10: digits and letters; iban: country code + BBAN to generate, or a full IBAN to validate. Use sample numbers only"
      },
      "action": {
       "type": "string",
       "description": "generate (default; value has no check digits yet) or validate (value includes them)"
      },
      "scheme": {
       "type": "string",
       "description": "luhn, mod97-10 or iban"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "iban": {
       "type": [
        "null",
        "string"
       ]
      },
      "scheme": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "ibanLength": {
       "type": [
        "null",
        "number"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "checkDigits": {
       "type": [
        "null",
        "string"
       ]
      },
      "countryCode": {
       "type": [
        "null",
        "string"
       ]
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/crypto-math-check-digits-4ae85252/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from crypto-math.x402tookit.com](https://www.zero.xyz/host/crypto-math.x402tookit.com/llms.txt)