In 1920, while on his death-bed, Ramanujan wrote a letter to his mentor, English mathematician G H Hardy, outlining several new mathematical functions never before heard of, along with a hunch about how they worked.
Researchers say they've proved he was right - and that the formula could explain the behaviour of black holes, the 'Daily Mail' reported.
"We have solved the problems from his last mysterious letters. For people who work in this area of math, the problem has been open for 90 years" Emory University mathematician Ken Ono said.
Born in a rural village in South India, Ramanujan, a self-taught mathematician, spent so much time thinking about mathematics that he flunked out of college twice, Ono said.
The maths genius's letter described several new functions that behaved differently from known theta functions, or modular forms, and yet closely mimicked them.
Functions are equations that can be drawn as graphs on an axis, like a sine wave, and produce an output when computed for any chosen input or value, the report said.
Ramanujan conjectured that his mock modular forms corresponded to the ordinary modular forms earlier identified by Carl Jacobi, and that both would wind up with similar outputs for roots of 1.
"It wasn