All require some preparation to use properly. The "dictionary test" is a gimmicked book test that anyone can prepare using any book, but works best with dictionaries, encyclopedias, books of lists, or other texts where there is some sort of obvious first word that is called out in the text. Using a dictionary, the gimmick is prepared by finding the first defined word on the left page, which is normally bolded or larger, and writing it in fine pencil on the top of the right page. The magician then holds the book open in front of the spectator and riffles with the left hand, and asks the spectator to call "stop" at any point. The magician then points to the upper right corner (blindly, as the book is still facing away from the magician) and while the spectator is looking there, peeks at the other corner, which is turned just enough to be visible. A commercial variation of the dictionary test is known as "Flashback," and comes in the form of a complete gimmicked book. Instead of the word appearing faintly at the top of the page, it is arranged so the last word on the left page is the same as the first word on the right page. In some forms the antonym appears on the mirror page, instead of the same word. For instance, if the word "day" appears as the first word on the left page, a straight flashback would put the word "day" on the left page, while an antonym version puts "night" there instead. Flashback variations are often incorporated in gimmick books supporting other methods as well. The "Page, Line and Word" trick uses two or three spectators, handing one a book (the "reader"), another an envelope, and the third pencil and paper (the "writer"). The writer is asked to "imagine" opening the book and selecting a word at random, and then writes down the page, line and word number they imagined. The magician then palms the writer's slip and hands a prepared slip to the reader, who opens the book to the selected section. The third spectator then opens the envelope to reveal the same word. The "1089 force" is a natural that relies on the mathematical manipulation of three-digit numbers such that the answer to a series of seemingly random operations will always result in the number 1089. The spectator is then asked to turn to page 108 and read the 9th word. Mathematical forces of this sort, similar to the original "labyrinth" type tests, are no longer common as these are widely known to the audience.