I think it would be a pizza because you can divide it into fractions and halfs and is interesting and different as maths is.
This is very interesting I am full-Asian and the first thing came to my mind was a loaf of bread. Probably more to do with having lived most of my life in New Zealand though.As I'm half-Asian, my answer would be rice. It is basic and essential, and can serve as a prime ingredient for a wide range of material (food for rice, research fields for math).
After the math teacher told the class that the area of a circle is πr2, the Kentucky mountain man said:
"Pie are not square! Pie are round! Cornbread are square!"