10 Actors Who Needed Doubles For Ridiculous Reasons

4. Russell Crowe Couldn't Convincingly Write Mathematic Equations - A Beautiful Mind

No matter how brilliant an actor might be, there are some innate aspects of certain professions that are virtually impossible to imitate within just a few weeks or months of research.

Short of pulling a Daniel Day Lewis-calibre feat of method acting, people in that profession will be able to recognise a faker a million miles away.

And that was the problem faced by Russell Crowe and director Ron Howard while shooting the Best Picture-winning drama A Beautiful Mind, where Crowe played legendary real-life mathematician John Nash.

Because Crowe was unable to convincingly write equations with the natural flow of an actual mathematician, Howard hired the film's math consultant, Dave Bayer, to also play Crowe's "hand double" for scenes which required an equation to be written down.

Hilariously, Bayer even trimmed his nails in order to match Crowe's, unaware that Crowe had since grown his out to match Nash's. As a result, Bayer had to wear acrylic fingernails for much of the shoot.