The 25-year-old actor portrays real-life numerical genius Srinivasa Ramanujan in forthcoming flick The Man Who Knew Infinity and no role could be more ironic for the star, due to the fact he struggles to calculate basic arithmetic.

"I'm terrible - I can barely figure out tips on a bill," he tells BBC News. "My dad is an accountant and I always let him down because I'm horrendously atrocious with maths, so to play one of the greatest mathematicians in history is quite the irony."

Ramanujan had no formal training in mathematics, but despite this he is considered to have advanced the field tremendously, especially the realms of number theory, infinite series and continued fractions. He travelled to the UK's Cambridge University to work with English professor and mathematician G.H. Hardy, played by Jeremy Irons, in 1914 and faced loads of prejudice while conducting the pioneering research.

The Indian legend passed away at the age of 32 in 1920 and Patel feels honoured to be telling Ramanujan's incredible story in the new film.

"You've got a guy that's come fresh off a boat from the middle of nowhere in South India to Cambridge, into a very snotty environment where he faces a lot of adversity, racism and prejudice," he explains.

"Hardy put his whole reputation on the line for this Indian man, but at the same time almost failed to see him as a human for a lot of it."

Patel became a breakout star in 2008 when he played the role of Jamal in Slumdog Millionaire, a movie centring on his character's memories of growing up in the slums of Mumbai. And although he was born and raised in London, Patel continues to be cast as Indian characters in movies, a pattern he is beginning to accept.

"The scripts that I'm offered are quite typecast," he shares. "But I'm starting to look at it as more of a blessing than a curse because I get to play characters like Ramanujan and bring great Indians from my heritage to the screen and tell their stories.

"Things are changing now because I've been around a bit longer, but I don't feel as typecast as I did when I first came on the scene."

The Man Who Knew Infinity reaches U.S. theatres on 29 April (16).