In chapters 14-16 of "The Devil's Arithmetic", how does Chaya remember her number on her arm?

Following the example of Rivka, Chaya remembers the number on her arm by associating each digit with an idea.  Chaya, whose number is J19724, says,

"J for Jew.  And 1 for me, alone.  I am very, very much alone.  And 9...in English it is pronounced 'nine', which is like the German word for no.  No, I will not die here...Seven is for...each and every day of the week I stay alive.  One day at a time.  Then 2 for Gitl and Shmuel, who are here in this place, too...And 4 is for my family, I think.  I almost remember them.  If I close my eyes they are there, hovering within sight.  But when I open my eyes, they are gone" (Chapter 14).

By making each digit in her number stand for something which is meaningful to her, Chaya defeats the purpose of the number, which is to dehumanize her.  She makes it instead a vehicle for remembering those things in life that are important to her, and as such, it gives her the courage and determination to do everything she can to survive.