{
  "address": "ce74932a68cf98d05183fd5863111d05",
  "category": "other",
  "question": "What is 30 mpg (US) in L/100km?",
  "answer": "7.84049 L/100km",
  "askedBy": {
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    "display": "method deck",
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    "id": null
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  "answeredBy": "method",
  "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
    },
    {
      "label": "Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices",
      "url": null
    }
  ],
  "supersedes": null,
  "supersededBy": null,
  "isSeed": false,
  "seedSource": null,
  "seedAttribution": null,
  "duplicateOfQid": null,
  "publishedAt": null,
  "unpublishedAt": null,
  "voteCount": 0,
  "queuedForSubstrate": false,
  "answerMethod": "method",
  "unsourced": false,
  "source": {
    "kind": "standard",
    "value": "NIST Special Publication 811 (2008 edition), Appendix B.8: mile = 1609.344 m exactly",
    "retrieved_utc": "2026-09-30T19:29:48Z"
  },
  "qsha256": "80879f0a7725aa6863f32f472c31961fa4a7d76a8508737e3fe328411614e5b9",
  "runOne": null,
  "cardContractVersion": "card_contract/1",
  "deck_id": "method-deck",
  "deck_title": "Method Deck",
  "method": {
    "name": "Fuel economy conversion",
    "version": "1",
    "source_url_or_file": "methods/fuel-economy-conversion.cjs",
    "sha256_of_method_file": "6891182584b8b81d6b26c1459d86b501b2bf5b7fd39f23728b2a990d12466408"
  },
  "receipt": {
    "inSubstrate": false,
    "local": true,
    "modelCallsAtMint": 0,
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  },
  "method_deck": {
    "inputs": [
      {
        "name": "value",
        "type": "number",
        "unit": "from_unit",
        "required": true,
        "description": "The fuel economy figure to convert",
        "min": 0
      },
      {
        "name": "from_unit",
        "type": "string",
        "required": true,
        "description": "Unit of the input value",
        "enum": [
          "mpg_us",
          "mpg_uk",
          "l_100km",
          "km_l"
        ]
      },
      {
        "name": "to_unit",
        "type": "string",
        "required": true,
        "description": "Unit to convert into",
        "enum": [
          "mpg_us",
          "mpg_uk",
          "l_100km",
          "km_l"
        ]
      }
    ],
    "outputs": [
      {
        "name": "result",
        "unit": "to_unit",
        "description": "The converted fuel economy figure"
      }
    ],
    "steps": [
      "Convert the input to km/L (the pivot unit): km/L = value directly if already km/L; km/L = 100/value if L/100km (an inversion, since L/100km is a reciprocal rate); km/L = value * 1.609344/3.785411784 if mpg (US); km/L = value * 1.609344/4.54609 if mpg (UK).",
      "Convert km/L to the target unit: value = km/L directly if km/L; value = 100/(km/L) if L/100km (an inversion); value = km/L * 3.785411784/1.609344 if mpg (US); value = km/L * 4.54609/1.609344 if mpg (UK).",
      "Round result to 6 significant figures."
    ],
    "constants": [
      {
        "name": "km_per_mile",
        "value": 1.609344,
        "unit": "km/mi",
        "source": 0
      },
      {
        "name": "liters_per_us_gallon",
        "value": 3.785411784,
        "unit": "L/gal",
        "source": 1
      },
      {
        "name": "liters_per_uk_gallon",
        "value": 4.54609,
        "unit": "L/gal",
        "source": 1
      }
    ],
    "examples": [
      {
        "name": "worked example",
        "inputs": {
          "value": 30,
          "from_unit": "mpg_us",
          "to_unit": "l_100km"
        },
        "expected": {
          "answer": "7.84049 L/100km"
        },
        "check": "By hand: km/L = 30 * 1.609344/3.785411784 = 12.754304...; L/100km = 100/12.754304... = 7.840486..., rounded to 6 significant figures is 7.84049."
      },
      {
        "name": "test vector: L/100km back to mpg (US) confirms the inversion",
        "inputs": {
          "value": 7.840486,
          "from_unit": "l_100km",
          "to_unit": "mpg_us"
        },
        "expected": {
          "answer": "30.0000 mpg (US)"
        },
        "check": "Inverting the worked example: km/L = 100/7.840486 = 12.754305...; mpg (US) = 12.754305 * 3.785411784/1.609344 = 30.0000..., recovering the original value."
      },
      {
        "name": "test vector: mpg (UK) to km/L",
        "inputs": {
          "value": 40,
          "from_unit": "mpg_uk",
          "to_unit": "km_l"
        },
        "expected": {
          "answer": "14.1602 km/L"
        },
        "check": "By hand: km/L = 40 * 1.609344/4.54609 = 14.16019...; rounded to 6 significant figures is 14.1602."
      }
    ],
    "disclaimer": null,
    "deck_category": "units"
  },
  "status": "minted",
  "kind": "method",
  "provenanceClass": "own_question",
  "provenance": {
    "schema": "card_provenance/2.0.0",
    "chain": [
      {
        "source": {
          "kind": "standard",
          "value": "NIST Special Publication 811 (2008 edition), Appendix B.8: mile = 1609.344 m exactly",
          "retrieved_utc": "2026-09-30T19:29:48Z"
        },
        "sha256": "0e1515ed3b265ad848924e05969c6e2ab14c503d3034bd3c0b7e76491f9c6446",
        "supersedes": null,
        "added_utc": "2026-09-30T22:39:30.722Z",
        "added_by": "method:Fuel economy conversion",
        "why": "the method that computed this answer",
        "check": null,
        "status_label": "pending",
        "signature": null
      }
    ]
  }
}