'Less' is already the comparative. You only use 'lesser' in English when you're talking about someone of a low rank or something of a low quality, like 'lesser priest'. But that's only used rarely either.
Somehow, when I first got this sentence, I typed 'Five is less than eight'. It was seen as incorrect, so the next time I typed 'Five is smaller than eight', but somehow that too was seen as incorrect. What am I supposed to say here?
In english it should be 5 is fewer than 8, because you can count it. There is a difference between fewer and less
Aha, there we are again with the difference between cardinal numbers (tal in Danish) and numerals (antal). :)
Numbers themselves are singular entities by definition, so "Five is less than eight" is the correct option. But if you start counting something, you get into the realm of plural objects: "Five apples are fewer than eight (apples)."
You have the same difference in Danish:
- Fem er mindre end otte.
- Fem æbler er færre end otte (æbler).