Rivka shares the rules she follows to stay alive at the camp one day at a time in The Devil's Arithmetic. What are they?No thank you.

These are the rules Rivka shares to help the others stay
alive at the camp one day at a time.

1. It is of
   utmost importance that each prisoner remember his or her own number, and to learn to
   read the numbers of others as if they were names. There are good numbers and bad
   numbers. For example, if someone has a G in her number, he or she
   is Greek. It is important not to stand nearby such a person. They do not speak Yiddish,
   and so do not understand German; because of this, they get in trouble  and are quickly
   eliminated, and anyone near them is likely to suffer the same consequence as well. Also,
   if a prisoner has a number lower than one's own, that prisoner has been at the camp
   longer, and is a survivor. As such, these survivors may be able to provide help to the
   newcomers.


2. It is important to learn to let people, even
   loved ones, go, if they no longer have the will to survive. It is also important to
   learn when to fight and when not to.


3. The prisoners must
   never go near the large wooden fence across the compound. There is a door in the fence,
   which is the door to a place dubbed "Lilith's Cave." To go through the door is to
   die.


4. When the commandant comes, it is the duty of every
   prisoner to help the children in the camp hide in the midden. Children are not supposed
   to be in the camp, but if they are hidden in the midden, which the Germans scrupulously
   avoid, nothing is said about them. As long as the commandant does not actually
   see the children, he lets them
   remain.

Hannah argues with Rivka that the rules
are "craziness," but Rivka says that nonetheless, they must still be followed if one
wishes to live. Nothing about the camp makes sense; it is the "devil's arithmetic," and
it is a skill that must be learned in order to survive (Chapter
14).