Questions & Answers about O homem tem um gato e zero problemas.
Is um acting as "a" or "one" in this sentence?
It actually does double duty! In Portuguese, the word for the number one (um for masculine words, uma for feminine) is the exact same word as the word for "a" or "an". Because the sentence contrasts it with zero later on, it makes the most sense to translate it as "one" here.
Why is problemas plural if there are zero of them?
Wait, doesn't ending in "-a" make problemas a feminine word?
Normally, yes! But problema is a very common exception. Words ending in "-ema" or "-oma" (which usually come from Greek) are masculine. If we had just one problem, we would say um problema, not uma problema.