Book 48 was the final part of Philip Reeve's series which began with Mortal Engines and ended with A Darkling Plain. It was well written, and ended with clearly even if not happily.
Another 'school' book borrowed from the library was John Grisham's The Summons and it was an ok story; I have read better works by him. There was more than one lawyer, it was set in the southern states of the USA... I am sure you get it!
Then Eoin Colfer's Artemis Fowl with the first book of the series made my 50th. I found it amusing that it was set in Dublin and when the lead character's mother wakes up she calls for deliveries from Brown Thomas, which was and is an upmarket fashion store...
So far this year 50 books and 14,084 pages.