"It was less than zero degrees."
Translation:Il faisait moins de zéro degré.
In English only the integer 1 is singular, anything else is plural including real numbers (e.g. It's 1.0 degrees vs Its only 1 degree). Is it not the same in French? So in English it's "zero degrees". Why isn't zero plural here? I wrote "If faisait moins de zéro degrés" and was marked wrong.
It's a difference between the languages. There are differences for some other numbers as well, i.e. in English, when dealing with specific numbers we don't add an 's' at the end of hundred, million, billion i.e. three hundred or four million. In French you would: trois cents, quatre millions. To make it confusing, in the case of thousands, its the same in French as in English, always singular.
In short: they're different languages, sometimes the grammar doesn't quite scan.
Consistent with other adverbs of quantity which use 'de'. See this web-page:
Is C'était moins de zéro degré right or wrong? Because that's what I did but I had gotten it wrong.
This sentence has an ambiguity. This is only the correct translation if we're talking about the weather. But if I refer to an specific object that was particularly cold, say, less than zero degrees, it no longer applies, and you'd have to say, if I'm not wrong, "c'était moins de zéro degrés", which was what I wrote, and was considered incorrect.