Mathematician
A mathematician is someone who studies and uses mathematics as his or her career.
Contrary to the belief in some circles, "mathematician" is not synonymous with "professor of mathematics", although that is arguably the most popular image of a mathematician: a person who does mathematical research at a college or university, along with teaching classes.
It is believed that the largest employer of mathematics in the United States is the National Security Agency.
Many other government agencies and private companies use mathematicians and specialize in mathematical modeling or operations research.