Fans watching a soccer game between Romania and Spain last March might have found a calculator handy. In an effort to boost students’ interest in math, Romania’s men’s soccer team swapped the numbers on their jerseys for mathematical expressions. The answers to the math problems revealed each player’s number.

The event was part of a countrywide project aimed at lowering the dropout rate among Romanian students, which is about 18%. The jerseys were worn only during warm-up, just in case the referees weren’t up to speed on their math skills.