{
  "address": "316a3543d6c12b1e3c8af03352a3b2b0",
  "category": "other",
  "question": "How many km are in 5 mi?",
  "answer": "8.04672 km",
  "askedBy": {
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  "madeAt": "2026-09-30T22:39:30.722Z",
  "validUntil": null,
  "validityClass": "forever",
  "sources": [
    {
      "label": "Guide for the Use of the International System of Units (SI)",
      "url": null
    }
  ],
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  "answerMethod": "method",
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  "source": {
    "kind": "standard",
    "value": "NIST Special Publication 811 (2008 edition), Appendix B.8, Table for length",
    "retrieved_utc": "2026-09-30T19:29:48Z"
  },
  "qsha256": "7e42a5b7439c3749353fb485571c87a8b239c62263a4e90aa277cde5c19f685b",
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  "cardContractVersion": "card_contract/1",
  "deck_id": "method-deck",
  "deck_title": "Method Deck",
  "method": {
    "name": "Length conversion",
    "version": "1",
    "source_url_or_file": "methods/length-conversion.cjs",
    "sha256_of_method_file": "58a4dfd117e24a31106c01005b67b7465886cc81f0216218da174c8dcfb3016c"
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  "receipt": {
    "inSubstrate": false,
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  },
  "method_deck": {
    "inputs": [
      {
        "name": "value",
        "type": "number",
        "unit": "from_unit",
        "required": true,
        "description": "The length to convert"
      },
      {
        "name": "from_unit",
        "type": "string",
        "required": true,
        "description": "Unit of the input value",
        "enum": [
          "mm",
          "cm",
          "m",
          "km",
          "in",
          "ft",
          "yd",
          "mi",
          "nmi"
        ]
      },
      {
        "name": "to_unit",
        "type": "string",
        "required": true,
        "description": "Unit to convert into",
        "enum": [
          "mm",
          "cm",
          "m",
          "km",
          "in",
          "ft",
          "yd",
          "mi",
          "nmi"
        ]
      }
    ],
    "outputs": [
      {
        "name": "result",
        "unit": "to_unit",
        "description": "The converted length"
      }
    ],
    "steps": [
      "Look up the exact meter-equivalent of from_unit and of to_unit from the NIST SP 811 table.",
      "Convert the input to meters: meters = value * meters_per(from_unit).",
      "Convert meters to the target unit: result = meters / meters_per(to_unit).",
      "Round result to 6 significant figures."
    ],
    "constants": [
      {
        "name": "mm",
        "value": 0.001,
        "unit": "m",
        "source": 0
      },
      {
        "name": "cm",
        "value": 0.01,
        "unit": "m",
        "source": 0
      },
      {
        "name": "m",
        "value": 1,
        "unit": "m",
        "source": 0
      },
      {
        "name": "km",
        "value": 1000,
        "unit": "m",
        "source": 0
      },
      {
        "name": "in",
        "value": 0.0254,
        "unit": "m",
        "source": 0
      },
      {
        "name": "ft",
        "value": 0.3048,
        "unit": "m",
        "source": 0
      },
      {
        "name": "yd",
        "value": 0.9144,
        "unit": "m",
        "source": 0
      },
      {
        "name": "mi",
        "value": 1609.344,
        "unit": "m",
        "source": 0
      },
      {
        "name": "nmi",
        "value": 1852,
        "unit": "m",
        "source": 0
      }
    ],
    "examples": [
      {
        "name": "worked example",
        "inputs": {
          "value": 5,
          "from_unit": "mi",
          "to_unit": "km"
        },
        "expected": {
          "answer": "8.04672 km"
        },
        "check": "By hand: 5 mi * 1609.344 m/mi = 8046.72 m = 8.04672 km exactly; already 6 significant figures."
      },
      {
        "name": "test vector: km to miles",
        "inputs": {
          "value": 100,
          "from_unit": "km",
          "to_unit": "mi"
        },
        "expected": {
          "answer": "62.1371 mi"
        },
        "check": "By hand: 100,000 m / 1609.344 m/mi = 62.137119...; rounded to 6 significant figures is 62.1371."
      },
      {
        "name": "test vector: inches to centimeters",
        "inputs": {
          "value": 12,
          "from_unit": "in",
          "to_unit": "cm"
        },
        "expected": {
          "answer": "30.4800 cm"
        },
        "check": "By hand: 12 in * 0.0254 m/in = 0.3048 m = 30.48 cm exactly, shown to 6 significant figures as 30.4800."
      }
    ],
    "disclaimer": null,
    "deck_category": "units"
  },
  "status": "minted",
  "kind": "method",
  "provenanceClass": "own_question",
  "provenance": {
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    "chain": [
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        "source": {
          "kind": "standard",
          "value": "NIST Special Publication 811 (2008 edition), Appendix B.8, Table for length",
          "retrieved_utc": "2026-09-30T19:29:48Z"
        },
        "sha256": "4351ccbea9ee623067efe3626fde8c4d0eacf418cf0235584702d2117a6bc1d5",
        "supersedes": null,
        "added_utc": "2026-09-30T22:39:30.722Z",
        "added_by": "method:Length conversion",
        "why": "the method that computed this answer",
        "check": null,
        "status_label": "pending",
        "signature": null
      }
    ]
  }
}