Lab - $unwind - 2 Decimals


I try to take only 2 decimals, but I get an error and I do not know how to solve it.

“avg”: {$divide:
[ { $trunc: { $avg: { $multiply: ["$imdb.rating", 100] } } },
100 ] } } },

@ Patricia_62551

Please follow Forum guidelines in the future and do not post code here. Thanks.

Here’s one way to truncate a result to 1 decimal place

$divide: [{ $trunc: { multiply: ["", 10] } }, 10]

Notice that the Lab question is looking for a 1 decimal answer as shown, not 2

{ "_id": "First Last", "numFilms": 1, "average": 1.1 }

Good luck.


“errmsg” : “$multiply only supports numeric types, not string”,

Hello @Memosha_53183,
just try to replace the empty space in the “multiple” expression to the rating field:wink:


Ummm… yes. That wasn’t intended and is not simply something to cut-and-paste. You need to read and understand the formula, then apply it. Try again. Good luck.

Its working fine now. Just added logic to use multiply correctly


Glad you got it working. Good luck.