<human>:  Why did the author choose to write about Srinivasa Ramanujan in the book ‘The Man Who Knew Infinity’?
<bot>: The author chose to write about Srinivasa Ramanujan because he was an interesting mathematician. He was born in India in 1887, and he was known for his mathematical genius. He died at the age of 32 in 1920, but he left behind a legacy of amazing work. He is known for the Ramanujan sum, which is a way to express a complicated number as a sum of simpler numbers.