The Adventures of Tintin (French: "Les Aventures de Tintin" ; ] ) is a series of 24 comic albums created by Belgian cartoonist Georges Remi, who wrote under the pen name Hergé.
 The series was one of the most popular European comics of the 20th century.
 By 2007, a century after Hergé's birth in 1907, "Tintin" had been published in more than 70 languages with sales of more than 200 million copies, and have been adapted for radio, television, theatre, and film.
Roberto Rastapopoulos is a fictional character in "The Adventures of Tintin", the comics series by Belgian cartoonist Hergé.
 He is a criminal mastermind with multiple identities and activities, and is said to be the main antagonist in the series.

Question: Rastapopoulos is in a series of how many? 
Answer: 24