Saylor Innovations Rule of 72 D
Rule of 72 doubling-time calculator - approximate and exact years to double
SearchLiveeip155:8453Exactvia cdp
FinanceXirrCagrRule-of-72Cashflow
Calls · 30d
1→ 0%
This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 19 snapshots so far.
$15.76
Verified settled volume
1,657 settlements proven x402 by their on-chain EIP-3009 marker.
$0.010
Listed price
As published in the catalog. Always read the live 402 before paying.
1
Calls · 30d
Upstream's own call count for this endpoint, not ours.
1
Unique payers · 30d
Last called 2026-10-12 13:25Z
—
Upstream on-chain volume
Reported by the source catalog.
Paid to
0xA2A8dF0f7CaaBEa4e120a2568118f141569fc8aaThe wallet the 402 directs payment to. Its whole payment record — every payer, every chain — is on the merchant page.
Asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
Provider
The payTo wallet does not resolve to a registered ERC-8004 agent. That is not a verdict on the service — most of the catalog is unregistered.
Live 402 challenge
Captured by the enrichment pass, not read just now. Prices can change — always read the 402 the endpoint answers with.
{
"error": "Payment required to access this resource.",
"accepts": [
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"memo": "saylor:finance:rule72",
"name": "USD Coin",
"note": "Base settles through an x402 facilitator. Send payload.signature and payload.authorization (EIP-3009); there is no self-submitted path on this network.",
"version": "2",
"facilitatorOnly": true,
"assetTransferMethod": "eip3009"
},
"payTo": "0xA2A8dF0f7CaaBEa4e120a2568118f141569fc8aa",
"amount": "10000",
"scheme": "exact",
"network": "eip155:8453",
"maxTimeoutSeconds": 120
},
{
"asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
"extra": {
"memo": "saylor:finance:rule72",
"session": "eyJhcnRpY2xlSWQiOiJmaW5hbmNlOnJ1bGU3MiIsInJlZmVyZW5jZSI6IjNQS2V0ZzZDSDl6RGlQQlYxSmo2bWNDRnVvelBpR2lIVHJjSjR5VDZtTUQzIiwicmVjaXBpZW50IjoiN0xTamZySmY4Zk5zQjhWQTl1N04zV0VuMjVzbVFMcG9iM1N2eVV2WGFjeTciLCJtaW50IjoiRVBqRldkZDVBdWZxU1NxZU0ycU4xeHp5YmFwQzhHNHdFR0drWnd5VER0MXYiLCJtaW5BbW91bnQiOjEwMDAwLCJleHAiOjE3OTE4MTQ3MDE3NDZ9.6-SsHlUrlzfeo5ob3vb-SIkxKVoC1-0Bs2cE1NOVNkA",
"feePayer": "D6ZhtNQ5nT9ZnTHUbqXZsTx5MH2rPFiBBggX4hY1WePM",
"reference": "3PKetg6CH9zDiPBV1Jj6mcCFuozPiGiHTrcJ4yT6mMD3"
},
"payTo": "7LSjfrJf8fNsB8VA9u7N3WEn25smQLpob3SvyUvXacy7",
"amount": "10000",
"scheme": "exact",
"network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
"maxTimeoutSeconds": 120
}
],
"resource": {
"url": "https://saylorinnovations.com/api/finance/rule72",
"tags": [
"finance",
"xirr",
"cagr",
"rule-of-72",
"cashflow"
],
"iconUrl": "https://saylorinnovations.com/og-image.jpg",
"mimeType": "application/json",
"description": "Rule of 72 doubling-time calculator - approximate and exact years to double",
"serviceName": "Saylor Innovations Rule of 72 D"
},
"extensions": {
"bazaar": {
"info": {
"input": {
"type": "http",
"method": "GET"
},
"output": {
"type": "json",
"example": {
"scope_note": "Educational growth-rate approximation only; not investment advice.",
"rate_percent": 6,
"rule_of_72_years": 12,
"exact_doubling_years": 11.9
}
}
},
"schema": {
"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",
"POST",
"PUT",
"PATCH",
"DELETE",
"HEAD"
],
"type": "string"
}
},
"additionalProperties": false
},
"output": {
"type": "object",
"required": [
"type"
],
"properties": {
"type": {
"type": "string",
"const": "json"
},
"example": {
"type": "object",
"required": [
"rate_percent",
"rule_of_72_years",
"exact_doubling_years",
"scope_note"
],
"properties": {
"formula": {
"type": "string"
},
"rounding": {
"type": "string"
},
"scope_note": {
"type": "string"
},
"rate_percent": {
"type": "number"
},
"service_note": {
"type": "string"
},
"assumption_note": {
"type": "string"
},
"rule_of_72_years": {
"type": "number"
},
"approximation_note": {
"type": "string"
},
"absolute_error_years": {
"type": "number"
},
"annual_growth_factor": {
"type": "number"
},
"exact_doubling_years": {
"type": "number"
}
}
}
}
}
}
}
},
"method": "GET",
"example": {
"scope_note": "Educational growth-rate approximation only; not investment advice.",
"rate_percent": 6,
"rule_of_72_years": 12,
"exact_doubling_years": 11.9
},
"license": "Saylor calculation and normalization; source standards/assumptions disclosed",
"mimeType": "application/json",
"freshness": "computed per request",
"tokenCount": null,
"description": "Estimate investment or metric doubling time from a constant annual percentage growth rate using both the Rule of 72 and exact logarithmic compounding, returning approximation error, formula, assumptions, and clear non-advice limitations.",
"inputSchema": {
"rate_percent": "required positive annual compound growth rate percentage (query)"
},
"serviceName": "Saylor Innovations — Rule of 72 Doubling-Time Calculator",
"instructions": "STANDARD PATH (works with stock x402 clients): send payload.transaction — a base64 partially-signed Solana transaction — and we route verify/settle through an x402 facilitator that sponsors the fee and submits it. Include the chosen accepts entry as \"accepted\" so we can match terms. ALTERNATIVE PATH (no facilitator): Pick ONE entry from accepts and use the reference and session from THAT entry — each asset has its own. USDC or USDT: send an SPL transfer of the exact amount. Native SOL (asset=So11111111111111111111111111111111111111112, extra.native=true): send that many lamports with a system transfer. Either way include extra.reference as a read-only account (Solana Pay style), then retry with PAYMENT-SIGNATURE: base64({x402Version:2, payload:{session, reference}}). If your client cannot attach a reference, send payload.signature instead (USDC only). SOL amounts are quoted live and expire in 120s; stablecoins do not move. The facilitator path verifies and settles in this request. Only the alternative self-submitted Solana path needs retries while the transfer is indexed (typically 3-4 attempts over 10-20s). On that path, a 402 saying \"payment not found on-chain yet\" means keep retrying.",
"outputSchema": {
"type": "object",
"required": [
"rate_percent",
"rule_of_72_years",
"exact_doubling_years",
"absolute_error_years",
"annual_growth_factor",
"formula",
"rounding",
"approximation_note",
"scope_note",
"service_note",
"assumption_note"
],
"properties": {
"formula": {
"type": "string"
},
"rounding": {
"type": "string"
},
"scope_note": {
"type": "string"
},
"rate_percent": {
"type": "number"
},
"service_note": {
"type": "string"
},
"assumption_note": {
"type": "string"
},
"rule_of_72_years": {
"type": "number"
},
"approximation_note": {
"type": "string"
},
"absolute_error_years": {
"type": "number"
},
"annual_growth_factor": {
"type": "number"
},
"exact_doubling_years": {
"type": "number"
}
}
},
"noPathTemplate": true,
"settlementModes": [
"facilitator-transaction",
"self-submitted-reference"
],
"typicalLatencyMs": 10
},
"x402Version": 2
}Accepts
The payment requirements as published to the catalog. Read the live 402 before paying — a price here is a claim, not a quote.
0.01USDC≈ $0.01 USD
on Base · exact scheme
Pay 0.01 USDC on Base to 0xA2A8…fc8aa. The signed payment is good for 2 minutes.
- Paid to
- 0xA2A8…fc8aa
- USD Coin contract
- 0x8335…02913
- Payment window
- 2 minutes
- As published
- 10000 smallest units
10000units
on solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- 7LSjfr…Xacy7
- Token contract
- EPjFWd…TDt1v
- Payment window
- 2 minutes
The catalog’s raw entry
[
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"memo": "saylor:finance:rule72",
"name": "USD Coin",
"note": "Base settles through an x402 facilitator. Send payload.signature and payload.authorization (EIP-3009); there is no self-submitted path on this network.",
"version": "2",
"facilitatorOnly": true,
"assetTransferMethod": "eip3009"
},
"payTo": "0xA2A8dF0f7CaaBEa4e120a2568118f141569fc8aa",
"amount": "10000",
"scheme": "exact",
"network": "eip155:8453",
"maxTimeoutSeconds": 120
},
{
"asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
"extra": {
"memo": "saylor:finance:rule72",
"session": "eyJhcnRpY2xlSWQiOiJmaW5hbmNlOnJ1bGU3MiIsInJlZmVyZW5jZSI6IjlXMlpKcFNpRmlTNkdMaExNTldDdUVDNEtRTkF6OHFNb3JmUG9ad0pSaGk3IiwicmVjaXBpZW50IjoiN0xTamZySmY4Zk5zQjhWQTl1N04zV0VuMjVzbVFMcG9iM1N2eVV2WGFjeTciLCJtaW50IjoiRVBqRldkZDVBdWZxU1NxZU0ycU4xeHp5YmFwQzhHNHdFR0drWnd5VER0MXYiLCJtaW5BbW91bnQiOjEwMDAwLCJleHAiOjE3OTE4MTE2NDk0ODN9.R7Y1GymHx9BHZhfidxWS3laKgB9RAbarTznZbScr4Fw",
"feePayer": "BENrLoUbndxoNMUS5JXApGMtNykLjFXXixMtpDwDR9SP",
"reference": "9W2ZJpSiFiS6GLhLMNWCuEC4KQNAz8qMorfPoZwJRhi7"
},
"payTo": "7LSjfrJf8fNsB8VA9u7N3WEn25smQLpob3SvyUvXacy7",
"amount": "10000",
"scheme": "exact",
"network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
"maxTimeoutSeconds": 120
}
]Extensions
{
"bazaar": {
"info": {
"input": {
"type": "http",
"method": "GET"
},
"output": {
"type": "json",
"example": {
"scope_note": "Educational growth-rate approximation only; not investment advice.",
"rate_percent": 6,
"rule_of_72_years": 12,
"exact_doubling_years": 11.9
}
}
},
"schema": {
"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",
"POST",
"PUT",
"PATCH",
"DELETE",
"HEAD"
],
"type": "string"
}
},
"additionalProperties": false
},
"output": {
"type": "object",
"required": [
"type"
],
"properties": {
"type": {
"type": "string",
"const": "json"
},
"example": {
"type": "object",
"required": [
"rate_percent",
"rule_of_72_years",
"exact_doubling_years",
"scope_note"
],
"properties": {
"formula": {
"type": "string"
},
"rounding": {
"type": "string"
},
"scope_note": {
"type": "string"
},
"rate_percent": {
"type": "number"
},
"service_note": {
"type": "string"
},
"assumption_note": {
"type": "string"
},
"rule_of_72_years": {
"type": "number"
},
"approximation_note": {
"type": "string"
},
"absolute_error_years": {
"type": "number"
},
"annual_growth_factor": {
"type": "number"
},
"exact_doubling_years": {
"type": "number"
}
}
}
}
}
}
}
}
}Provenance
- Seen in the source catalog
- 2026-10-12 13:25Z
- Last indexed by Roundhouse
- 2026-10-26 17:50Z
- Last enriched (probe, favicon, geo)
- 2026-10-12 14:16Z
- x402 version
- 2
- Max timeout
- 120s
- Liveness probe
- HTTP 402
Hand this page to an agent
Copy the prompt and paste it into Claude, an MCP client or your own agent — it will vet this service and call it over the free read API. No key, no account.
GET api.roundhouseai.io/v0/endpoints
This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 19 snapshots so far. Verified volume counts only settlements with an on-chain EIP-3009 marker.
Show the promptHide the prompt
Using Roundhouse, look up the x402 service Saylor Innovations Rule of 72 D and tell me whether it is worth paying: what a call costs, whether the endpoint answered when last probed, and what its payment record actually shows. curl -s 'https://api.roundhouseai.io/v0/endpoints?q=Saylor%20Innovations%20%20Rule%20of%2072%20D' curl -s 'https://api.roundhouseai.io/v0/merchants/<the payTo wallet returned above>' Then call it: read the price from the live 402 at https://saylorinnovations.com/api/finance/rule72, never from a cached figure, and pay with an x402 client. The /v0 API needs an API key (`authorization: Bearer rh_live_…`) on everything except /v0/unified* and /v0/endpoints. Either pay over x402 (mint a personal key for $0.01 at GET https://api.roundhouseai.io/v0/test/x402), or ask me for an organization key, which I create at https://roundhouseai.io/dashboard/connections. If you have neither, ask before going further. If you do not have Roundhouse tools or skills installed, read https://roundhouseai.io/skill.md first — it is the whole procedure.