Out of the three U.S. team members from the Bay Area, two won silver and one brought back a gold. Over 200 girls from ten countries competed.
The contestants say the math questions were different than what they're used to in school.
"In school you memorize some theorems and then you apply them, but for here you have to think of different ways in which to use them," Cynthia Day said.
The girls were given problems that each took an hour to solve.
All eight members of the U.S. team won medals this year.