Harry Potter has transformed countless lives aged 8 to 80 and yet, J.K. Rowling has had to mourn over the loss of one thing ...

and if J.K. Rowling took a standard authors royalty cut of 15%, she would have made at least $1.15 billion, and that's before accounting for the movie series, which have also grossed $7.7 billion ...

J.K. Rowling, a single mother at the time, faced immense pressure to finish the first Harry Potter book before starting her teacher training.

A new infographic shows us the pens and typewriters authors like JK Rowling and Agatha Christie ... which was what she used to create her famous detectives Poirot and Miss Marple.