freeCodeCamp/curriculum/challenges/english/blocks/daily-coding-challenges-python/69f35a5bb823ed620fcb7cb9.md

id, title, challengeType, dashedName

id	title	challengeType	dashedName
69f35a5bb823ed620fcb7cb9	Challenge 280: Mongo ID Date	29	challenge-280

--description--

Given a MongoDB ID string, return its creation time as an ISO 8601 string.

• A MongoDB ID is a 24-character hex string. The first 8 characters represent a Unix timestamp (in seconds) encoded as a base-16 integer.

For example, "6a094b50bcf86cd799439011" has a timestamp of "6a094b50" in hex, which is 1778994000 in decimal, representing a creation time of "2026-05-17T05:00:00.000Z".

--hints--

mongo_id_to_date("6a094b50bcf86cd799439011") should return "2026-05-17T05:00:00.000Z".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(mongo_id_to_date("6a094b50bcf86cd799439011"), "2026-05-17T05:00:00.000Z")`)
}})

mongo_id_to_date("695344eb1f4a4c1123042128") should return "2025-12-30T03:20:11.000Z".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(mongo_id_to_date("695344eb1f4a4c1123042128"), "2025-12-30T03:20:11.000Z")`)
}})

mongo_id_to_date("386da62df34123ac54617e56") should return "2000-01-01T07:01:01.000Z".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(mongo_id_to_date("386da62df34123ac54617e56"), "2000-01-01T07:01:01.000Z")`)
}})

mongo_id_to_date("69f571c3d7711807afd3dd55") should return "2026-05-02T03:38:43.000Z".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(mongo_id_to_date("69f571c3d7711807afd3dd55"), "2026-05-02T03:38:43.000Z")`)
}})

mongo_id_to_date("68adce01c0e1144d0a90295a") should return "2025-08-26T15:08:49.000Z".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(mongo_id_to_date("68adce01c0e1144d0a90295a"), "2025-08-26T15:08:49.000Z")`)
}})

--seed--

--seed-contents--

def mongo_id_to_date(s):

    return s

--solutions--

from datetime import datetime, timezone

def mongo_id_to_date(s):
    timestamp = int(s[:8], 16)
    dt = datetime.fromtimestamp(timestamp, tz=timezone.utc)
    return dt.strftime("%Y-%m-%dT%H:%M:%S.000Z")