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   "source": [
    "# [Pandigital Multiples](https://projecteuler.net/problem=38)\n",
    "\n",
    "Any number with five or more digits will have a concatenated product with more than 9 digits. Therefore we only need to check numbers with less than five digits."
   ]
  },
  {
   "cell_type": "code",
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   "id": "ffea7112",
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    {
     "data": {
      "text/plain": [
       "932718654"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "from itertools import count\n",
    "\n",
    "def is_pandigital(s):\n",
    "    return ''.join(sorted(s)) == \"123456789\"\n",
    "\n",
    "\n",
    "pandigitals = set()\n",
    "for k in range(1, 10000):\n",
    "    s = \"\"\n",
    "    for n in count(1):\n",
    "        s += str(k * n)\n",
    "        if len(s) >= 9:\n",
    "            break\n",
    "    \n",
    "    if is_pandigital(s):\n",
    "        pandigitals.add(int(s))\n",
    "\n",
    "        \n",
    "max(pandigitals)"
   ]
  }
 ],
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