I'd forgive an entry-level candidate (straight out of college) for not knowing about the modulo operator. We had one who solved it correctly using floor/ceilin

I'd forgive an entry-level candidate (straight out of college) for not knowing about the modulo operator. We had one who solved it correctly using floor/ceiling. If they're claiming 3+ years of experience though, I'd say not knowing about modulo is a red flag. It means they're being dishonest about their actual experience, or those 3+ years of experience are very narrow, and/or they're not terribly curious about the field.