There are many different editions of Fahrenheit 451, so the page number will depends on publisher, typesetting, print size, and many other factors. In addition, there are abridged copies (such as Reader's Digest editions) and ebook editions, some of which have no page numbers to allow for different screen sizes and software.
In Google Books, the available copy is the 2003 Simon and Schuster edition, scanned for preview. In this edition, the quote above appears on page 78, during the scene where Montag visits Faber and tries to convince him that they could print more books to replace the ones that are being burned. The quote is spoken by Montag, as he tries to figure out why his previously-enjoyable life feels so empty and meaningless; he realizes that the only thing that has changed is that he has burned books, removing them from his life entirely.