The Question and Answer section for MAUS is a great resource to ask questions, find answers, and discuss the novel.
Vladek's number was 175113. A priest told him that 18, the total of his numbers, is the number for Chai in Hebrew, which means life.
The obvious answer is that there are Jews hung by the Germans. There are a few possibilities here as well. Vladek is not telling the truth about his wife's diary and exactly how she died. Art is getting closer to the truth. Vladek is also...
I think Vladek wanted someone to take care of him. The marriage is not a happy one. Vladek is abusive to Mala.He is paranoid that Mala wants his money. Mala puts up with a lot from Vladek.