the402 endpoint detail

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combinatorics.openverbs.com v1 factorial

https://combinatorics.openverbs.com/v1/factorial

answers 402

Exact factorial n! for 0 ≤ n ≤ 20000, returned as a decimal string with its digit count.

We sent a real POST request to this endpoint and it answered 402 with payment requirements we could parse.
Price
$0.004
Network
base
Pay to
0xb3f4de103F34b99f0Da19B4F16D6B53a14C2194A
Spec dialect
v2 (declares x402Version 2)
Transport
PAYMENT-REQUIRED header
HTTP method
POST
Response latency
277 ms
Payment options
1 usable of 1
Last checked
2026-09-06T01:20:10.810Z (23d ago)
Category
other

Re-check it yourself:
curl "https://api.the402.dev/validate?url=https%3A%2F%2Fcombinatorics.openverbs.com%2Fv1%2Ffactorial"