Thanks, Michael2, johnnyG and Lothor.
I know British people say maths while Americans say math. In the textbooks used here in Japan, American English is dominant. So we usually learn "math" when we are in junior high school. I learned(/learnt) in college that British people use "maths" instead of "math".
JohnnyG's daughter had an interesting experience. How old was she when you took her there? By the way, did you understand New Zealanders' English easily? When I talked with a young teacher from New Zealand for the first time several years ago, I couldn't catch his pronunciation of "first". His accent was really hard for me to understand.