There's a tendency towards "pronounced interests", but it doesn't have to be maths or anything science/maths/technology-related. Autism in girls gets missed a lot because they're just as obsessed/passionate as boys about their special interests, but it gets ignored because a) girls tend to be quieter about it (having been told to shut up and let other people talk); and b) girls' special interests can be more in line with what "normal girls are supposed to be interested in". Stuff like celebrities, horses, or reading. You know, girl stuff. [eyeroll] Or at least, not trains.
Nor do you have to be good at something for it to be a special interest.
I always think of it as that the autistic attitude seems to be (to misquote Lois McMaster Bujold): Anything worth doing is worth doing excessively.
In my life:
- Reading definitely counts as a 'special interest'. It was always a joke in my family that I'd read toffee papers if nothing else was available. I always read the back of the cereal packet at breakfast.
- Some people manage to learn to fly without ending up running the airfield. But not me...
- Most people don't have an indexed database of >6K research articles on multiple topics... just in case.