{
  "endpoint": "rule-of-72",
  "inputs": {
    "rate": 8
  },
  "result": {
    "years": 9,
    "exactYears": 9.01
  },
  "notes": [
    "The Rule of 72 is a mental-arithmetic approximation. It is accurate to within a few months over the 5%–12% range and drifts outside it — `exactYears` is the number to use when precision matters."
  ],
  "meta": {
    "source": "https://farbetteroff.com",
    "calculator": "https://farbetteroff.com/calculators/compound-interest-calculator",
    "docs": "https://farbetteroff.com/api/v1",
    "disclaimer": "Educational estimate, not financial advice."
  }
}