Charles Jean de la Vallée-Poussin

Charles Jean de la Vallée-Poussin (pronounced shahr-luh zhahn duh lah vah-leye-poos-san) was a really smart man who lived a long time ago. He was born in Belgium in 1866. He was a mathematician, which means he really liked numbers and solving problems with them. He studied math at a university in Belgium and then started teaching there when he was just 22 years old!

One of the things Charles Jean de la Vallée-Poussin is most famous for is something called the prime number theorem. This is a really big and complicated idea, but basically it helps us understand how many prime numbers there are (prime numbers are numbers that can only be divided by 1 and themselves, like 2, 3, 5, 7, and so on).

Charles Jean de la Vallée-Poussin worked really hard on this project for many years. He even had to create a new math tool called "complex analysis" to help him with his research. In 1896, he finally finished his work and proved the prime number theorem, which was a really big deal in the math world.

Charles Jean de la Vallée-Poussin went on to do many other important things in math. He taught at the university for many years and continued to research and discover new things. He passed away in 1962, but his work is still remembered and studied by mathematicians today.