- When a customer submitted their signup form to Dialup World, they would add a
    row for that new customer to their 20,000-row Excel spreadsheet. Then, they 
    would put that signup form in a pile with all the other signup forms of
    customers who had signed up on that day of the month. 
    
    - Every day, they would find which one of the 31 piles of literal signup forms 
    corresponded to that day of the month. 
    
    - Then, they’d charge the customers in that pile, one by one, for a month of 
    service.

Well, if you hop into a time machine and need dial-up access from "Dialup World" back in the 1990s, I guess there's a sweet hack -- sign up on the 31st of the month and you only get billed 7 times a year.