LONDON, Oct. 8 (UPI) -- Keira Knightley was baffled by the math of The Imitation Game.
The 29-year-old actress admitted as such at the BFI Film Festival in London. Knightley portrays real-life codebreaker Joan Clarke in the historical thriller, but said she and her co-stars struggled to understand the complex math utilized by their characters.
"It was that feeling I haven't had since school being in maths, of you sort of feel like you've died, of not being able to concentrate at all," she recalled of the cast's lesson from a math expert. "And I desperately wanted to because he was such a nice man, and I was thinking, 'This is really interesting, I should be paying attention.' But I couldn't."
"One day we decided we should all really do the crossword," she shared. "So we got the quick crossword. There were five of us, it took us five days, and we still didn't finish it. We were really bad at all of it. And I didn't understand any of the maths."
The Imitation Game stars Benedict Cumberbatch as real-life mathematician Alan Turing, a brilliant logician who helped break Nazi Enigma codes during WWII. Although his work contributed greatly to Allied success, he was later criminally prosecuted for homosexuality and died of an apparent suicide at age 41 in 1954. The film is directed by Morten Tyldum, and opens in theaters Nov. 21.