Mathematician Reincarnated into Magical World

After getting hooked with reading novels and melting in fantasy world, I had always wondered: what advantage would I have over the people in these 'fantasy' world if I was to he transferred there in their place somehow. Would biology help me if there is healing magic or physics when laws of nature could be defined by magic, or politics when there is no democracy or English when it is not even spoken there and so on. However there is one subject that is independent of place, situation, race, rules and what not. That is Maths. Mathematics is the only subject that works in every field and in everyday life no matter sci-fi or fantasy. And it just happened to be that I liked maths and am good at it. Let's define everything from the very basic of thinking and the fundamental of logic.