What is the crumb rate?

The question is understandable. Chametz on Passover is forbidden to eat and enjoy, and its share is the same as the law for kezait. But there is a half-share law, as with all Torah prohibitions, and therefore there is a prohibition on eating even less than kezait. There is also a separate prohibition on a mixture of chametz. And yet, from the explanation, it seems that there is a minimum size and there is no need to get hysterical. But you do need to clean as much as you can. I once heard Rabbi Ben Zion Abba Shaul asked whether it is permissible to drink water from the Sea of ​​Galilee despite the fear that someone had thrown some bread there, and he replied that even "something" has a limit. But you can't give a ration for this, of course, and the rule of thumb is to clean as much as you can without hysteria.