Question: Heatstroke stars an actress who has written how many non-fiction books?

Related documents: [0]  [DOC] Heatstroke is a Sci Fi Channel original movie. The film stars D. B. Sweeney and Danica McKellar. It was made by the team that made "Farscape". The film was written by Richard Manning and David Kemper, produced by David Kemper, and directed by Andrew Prowse. [END] 
[1]  [DOC] Danica Mae McKellar (born January 3, 1975) is an American actress, mathematics writer, and education advocate. She played Kevin Arnold's on-off girlfriend Winnie Cooper in the television series "The Wonder Years", and later wrote five non-fiction books: "Math Doesn't Suck", "Kiss My Math", "Hot X: Algebra Exposed", "Girls Get Curves: Geometry Takes Shape", which encourage middle-school and high-school girls to have confidence and succeed in mathematics, and "Goodnight, numbers". From 2010-2012 and 2018–present, McKellar voiced Miss Martian in the animated superhero series Young Justice. In 2015 Mckellar was cast in the Netflix original series "Project Mc". [END]  
Answer: five
five