Calculate the number 8731

Morris calls his son in NY and says, "Benny, I have something to tell you. However, I don't want to discuss it. I'm merely telling you because you're my oldest child, and I thought you ought to know. I've made up my mind, I'm divorcing Mama."The son is shocked, and asks his father to tell him what happened."I don't want to get into it. My mind is made up.""But Dad, you just can't decide to divorce Mama just like that after 54 years together. What happened?""It's too painful to talk about it. I only called because you're my son, and I thought you should know. I really don't want to get into it anymore than this. You can call your sister and tell her. It will spare me the pain.""But where's Mama? Can I talk to her?""No, I don't want you to say anything to her about it. I haven't told her yet. Believe me it hasn't been easy. I've agonized over it for several days, and I've finally come to a decision. I have an appointment with the lawyer the day after tomorrow.""Dad, don't do anything rash. I'm going to take the first flight down. Promise me that you won't do anything until I get there.""Well, all right, I promise. Next week is Passover. I'll hold off seeing the lawyer until after the Seder. Call your sister in NJ and break the news to her. I just can't bear to talk about it anymore."A half hour later, Morris receives a call from his daughter who tells him that she and her brother were able to get tickets and that they and the children will be arriving in Florida the day after tomorrow."Benny told me that you don't want to talk about it on the telephone, but promise me that you won't do anything until we both get there." Morris promises. After hanging up from his daughter, Morris turns to his wife and says, "Well, it worked this time, but we are going to have to come up with a new idea to get them here for Rosh Hashanah."