On the first page of this mystery set in 1920's India, a scrap of paper identifies the person a desperate character seeks:
(quoted from The Bangalore Detectives Club)
MRS KAVERI MURTHY, Mathematician and Lady Detective.

The rest of the novel is a flashback which mostly focuses on how she came to be a "lady detective".
The mystery itself is quaint and oldfashioned, despite its 21st century viewpoint on issues like gender equality, caste, and colonialism. Kaveri's husband  a doctor whom she married when she was a young girl but has only recently moved in with  is a kind and forward thinking individual who respects her intellect and desire to find the person responsible for a series of horrific attacks. By the end of the novel, after the reader has been introduced to a variety of suspects (and recipes), Kaveri does find the guilty party and hence becomes a detective.
However, in this novel, she really does not earn the title "mathematician". We only learn that she is the daughter of a math teacher and was a talented student of mathematics herself:
(quoted from The Bangalore Detectives Club)
It was her motherinlaw's nap time, i.e. the perfect time
for Kaveri to take an algebra lesson.
Ten minutes later, she was deep in thought and frowning
over a question at the kitchen table.
If 9 lbs of rice cost as much as 4 lbs of sugar, and 14 lbs of
sugar are worth as much as ½ lb of tea, and 2 lbs of tea are
worth as much as 5 lbs of coffee, what is the cost of Il lbs of
coffee if 2 ½ lbs of rice cost 6 ¼ d?
She hummed as she worked. All those hours of leaning
against her father's knee as he marked his students'
calculus
papers had certainly paid off, Kaveri thought smugly. She
had been as good as any boy in class  in fact, why be modest,
better  and it was not for nothing that she topped the exam
in her school every year. But now she was a married woman,
there were no more termtimes, no more calculus papers and
no more matriculation. If she wanted to study, she would
have to do so on stolen time.
She wished her motherinlaw was more supportive of her
passion for mathematics, so she would not have to study in
secret like this, furtively, like a criminal.

She later says that her goal is to get a degree in math and teach at a women's college. But, aside from that, math is barely mentioned again.
There is one paragraph which suggests that solving a murder mystery differs from mathematics where the questions are all clear and straightforward, like "2+3". I disagree with that statement, and hope that in future books in this series, Kaveri earns the title "mathematician" and also learns that the questions in math research can be as enigmatic as the ones encountered by a detective. 