"exercise for the reader" meaning in English

{
  "etymology_text": "From academic writing. One of the first known recorded occurrences of this phrase is in An Elementary Course of Mathematics by Thomas Stephens Davies, Stephen Fenwick, and William Rutherford from 1853.",
  "head_templates": [
    {
      "args": {
        "1": "!"
      },
      "expansion": "exercise for the reader (plural not attested)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "glosses": [
        "Used other than figuratively or idiomatically: see exercise, for, the, reader."
      ],
      "id": "en-exercise_for_the_reader-en-noun-mCyXOQFh",
      "links": [
        [
          "exercise",
          "exercise#English"
        ],
        [
          "for",
          "for#English"
        ],
        [
          "the",
          "the#English"
        ],
        [
          "reader",
          "reader#English"
        ]
      ],
      "tags": [
        "no-plural"
      ]
    },
    {
      "categories": [
        {
          "_dis": "26 74",
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "34 66",
          "kind": "other",
          "name": "English nouns with unattested plurals",
          "parents": [
            "Nouns with unattested plurals",
            "Nouns",
            "Lemmas"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "19 81",
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "13 87",
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w+disamb"
        }
      ],
      "examples": [
        {
          "ref": "2003, Wells Earl Draughon, Advanced Writing: Fiction and Film, iUniverse, →ISBN, page 167:",
          "text": "She does not ask to see the dossier on this man before she goes, even though the co-worker has said that he has seen it, etc. The credibility of this conduct is another matter and is left as an exercise for the reader.",
          "type": "quote"
        },
        {
          "ref": "2006, Hossein Bidgoli, Handbook of Information Security, Information Warfare, Social, Legal, and International Issues and Security Foundations, John Wiley & Sons, →ISBN, page 413:",
          "text": "Moreover, determining what is “passionate,” “artistic,” and “suitable for young children” is left as an exercise for the reader.",
          "type": "quote"
        }
      ],
      "glosses": [
        "A matter left to the addressee's judgement to decide."
      ],
      "id": "en-exercise_for_the_reader-en-noun-ATgDykDt",
      "links": [
        [
          "matter",
          "matter#English"
        ],
        [
          "addressee",
          "addressee#English"
        ],
        [
          "judgement",
          "judgement#English"
        ],
        [
          "decide",
          "decide#English"
        ]
      ],
      "raw_glosses": [
        "(by extension) A matter left to the addressee's judgement to decide."
      ],
      "tags": [
        "broadly",
        "no-plural"
      ]
    }
  ],
  "word": "exercise for the reader"
}

{
  "categories": [
    "English countable nouns",
    "English entries with incorrect language header",
    "English lemmas",
    "English multiword terms",
    "English nouns",
    "English nouns with unattested plurals",
    "Pages with 1 entry",
    "Pages with entries"
  ],
  "etymology_text": "From academic writing. One of the first known recorded occurrences of this phrase is in An Elementary Course of Mathematics by Thomas Stephens Davies, Stephen Fenwick, and William Rutherford from 1853.",
  "head_templates": [
    {
      "args": {
        "1": "!"
      },
      "expansion": "exercise for the reader (plural not attested)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "glosses": [
        "Used other than figuratively or idiomatically: see exercise, for, the, reader."
      ],
      "links": [
        [
          "exercise",
          "exercise#English"
        ],
        [
          "for",
          "for#English"
        ],
        [
          "the",
          "the#English"
        ],
        [
          "reader",
          "reader#English"
        ]
      ],
      "tags": [
        "no-plural"
      ]
    },
    {
      "categories": [
        "English terms with quotations"
      ],
      "examples": [
        {
          "ref": "2003, Wells Earl Draughon, Advanced Writing: Fiction and Film, iUniverse, →ISBN, page 167:",
          "text": "She does not ask to see the dossier on this man before she goes, even though the co-worker has said that he has seen it, etc. The credibility of this conduct is another matter and is left as an exercise for the reader.",
          "type": "quote"
        },
        {
          "ref": "2006, Hossein Bidgoli, Handbook of Information Security, Information Warfare, Social, Legal, and International Issues and Security Foundations, John Wiley & Sons, →ISBN, page 413:",
          "text": "Moreover, determining what is “passionate,” “artistic,” and “suitable for young children” is left as an exercise for the reader.",
          "type": "quote"
        }
      ],
      "glosses": [
        "A matter left to the addressee's judgement to decide."
      ],
      "links": [
        [
          "matter",
          "matter#English"
        ],
        [
          "addressee",
          "addressee#English"
        ],
        [
          "judgement",
          "judgement#English"
        ],
        [
          "decide",
          "decide#English"
        ]
      ],
      "raw_glosses": [
        "(by extension) A matter left to the addressee's judgement to decide."
      ],
      "tags": [
        "broadly",
        "no-plural"
      ]
    }
  ],
  "word": "exercise for the reader"
}