## 150. Math Puzzle 11/77

For their coming-of-age ceremony, all students in a class had individual photographs taken. Each student had enough prints made of their portrait to exchange with every classmate. In total, 812 photos were exchanged.

How many students are in the class?
In the class, there are 29 students. Each of the 29 gave their picture to 28 friends. A total of $28 \cdot 29=$ 812 photos were exchanged!