Rogue Kat It's explained in the book, why the title is "The Devil's Arithmetic." The death of each Jew is added to the Devil's abacus. Some lived longer than others, and others were sentenced to death upon their arrival to the camp. One's life sacrificed to save another's. In the book, she also refers to it as being the days of survival in the concentration camp added up, one by one.
Amanda Hill The Devil's Arithmetic is about the Holocaust. The "Devil" could literally be considered Hitler, but in this book it refers more to the general horror of the Holocaust. During the Holocaust, numbers were tattooed on the arms of Jews for identification. In the book, the Jews would make up stories about what each number stood for. This is where "Arithmetic" comes from. The numbers and their stories are the arithmetic of the devil, or "The Devil's Arithmetic" (I hope that makes sense)