even one is enough to pollinate the entire plant if you are using circulating fans in your room i suggest turning them off leave extract fans on and try not bump the plant or move it so the pollen don't become air born and cross your fingers not too much of the plant gets pregnant .
pollen spreads very easily so if you are picking them off and you see a big puff of pollen over the plant your going to get seeds
lots of things can make a plant produce them