As a single mother, Rowling became an international literary sensation in 1999 when the first three installments of her Harry Potter children's book series. The fourth volume, Harry Potter and the Goblet of Fire, became the fastest-selling book in history. Rowling graduated from Exeter University and moved to Portugal in 1990. Her marriage ended in divorce, and soon found herself on welfare. She sold the first book, Harry Potter and the Sorcerer's Stone for around 4,000.00. Rowling is currently Britain's 13 wealthiest. The 7th book in the series, harry Potter and the Half Blood Prince, sold 6.