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agent402.tools Combinatorics Calculator
x402
agent402.tools Combinatorics Calculator is a paid API for AI agents from agent402.tools, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).
Computes exact combinations C(n,r) or permutations P(n,r) using arbitrary-precision BigInt arithmetic, returning the result as a string and human-readable formula
Price / call$0.001
Success—
StatusUnknown
How this service works
Compute combinations C(n, r) or permutations P(n, r) using BigInt for exact arbitrary-precision results. Returns the result as a string (since values can exceed Number.MAX_SAFE_INTEGER) and a human-readable formula.
Output
Returns a JSON object containing the exact numeric result as a string (to handle values beyond Number.MAX_SAFE_INTEGER), the computation type (combination or permutation), and a human-readable formula like C(49,6) = 13,983,816
Example use cases
Example prompt
“How many ways can I choose 6 numbers from a pool of 49? Calculate the combination C(49, 6) and give me the exact result.”
Technical details
Endpoint
POSThttps://agent402.tools/api/combinatoricsWhen to prefer
Choose this endpoint when you need exact, arbitrary-precision combinatorics results that would overflow JavaScript's Number.MAX_SAFE_INTEGER — particularly for large n values (e.g. n > 60) where floating-point approximations would lose precision. Prefer over manual factorial computation or math libraries when you need a reliable, hosted solution with BigInt guarantees.
Side effects
- r > n returns an error (invalid selection size)
- n or r outside 0–1000 range returns a validation error
- invalid type string (not 'combination' or 'permutation') returns a bad request error
- missing required parameters n or r returns a 400 error
- payment not included or insufficient returns 402 Payment Required
Input
{
"n": 49,
"r": 6,
"type": "combination"
}Schema · Request body
| Field | Type | Description |
|---|---|---|
| n | integer | Total items (0 to 1000) |
| r | integer | Items chosen (0 to n) |
| type | string | "combination" (default) or "permutation" |
Output
{
"n": 49,
"r": 6,
"type": "combination",
"result": "13983816",
"formula": "C(49,6) = 49! / (6! × 43!)"
}Schema · Response
{
"type": "json",
"example": {
"n": 10,
"r": 3,
"type": "combination",
"result": "120",
"formula": "C(10,3) = 10! / (3! × 7!)"
}
}Tags
x402
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