What is the missing number?

Hospital regulations require a wheel chair for patients being discharged. However, while working as a student aide, Sam found one elderly gentleman already dressed and sitting on the bed with a suitcase at his feet, who insisted he didn't need Sam's help to leave the hospital. After a chat about rules being rules, he reluctantly let Sam wheel him to the elevator. On the way down Sam asked him if his wife was meeting him. I don't know, he said. She is still upstairs in the bathroom changing out of her hospital gown.