- On LDOCE (fifth definition), the word 'number' is listed as an uncountable noun meaning an amount of something that can be counted. So, controversially, I think that it is possible to use Hussein's first sentence even if it isn't idiomatic.
Actually, it wasn't mine, Ahmed. I just excerpted it from here:
My supervisor corrected it by adding "a" before "less", then I thought about some alternatives that might be used but wasn't sure, so I decided to ask here.