This may sound silly, but from the error message it looks like the exercise instructions asked you to use -100 as the value for the parameter (number), but you used 12 instead... Try going back and reading the instructions for the exercise again; maybe you just chose a different value than the question was specifically asking for (I've done that many times, much to my frustration.) When I ran your code with -100 as the value when calling the function, it gave me -25, so this is just a guess based off of the code you gave and the error message you provided-- Copying the instructions for the exercise to include with this question would be helpful so we could see exactly what it was asking you to do in the first place.
I hope this helps! If not, good luck!
PS. I think konaesan is correct in suggesting return instead of console.log, as well (just judging by the error message again).