J.K. Rowling’s Harry Potter series is known by everyone and loved by many but one installment of the series stands out above the others for its popularity.

The first novel in the series, Harry Potter and the Philosopher’s Stone, has sold in excess of 120 million copies, making it one of the bestselling books in history. 

The Harry Potter brand has been estimated to be worth as much as £19.34 billion.

Rowling’s books have sold more than 600 million copies worldwide, making them the…