Mary Clem facts for kids

Mary A. Clem (born Mary A. McLaughlin; 1905–1979) was an American mathematician. She was also known as a "human computer." This was a job where people did complex math calculations by hand.

Mary worked at Iowa State University. She became famous for inventing a special way to find mistakes in math. She called it the "zero check" technique.

About Mary Clem

Mary Clem was born on October 19, 1905. Her hometown was Nevada, a small place in Story County, Iowa.

Early Career

After high school, Mary worked for a few years. She was a computing clerk and bookkeeper. She worked for the Iowa State Highway Commission. She also worked for Iowa State College.

Becoming a Human Computer

In 1931, Mary joined the Mathematics Department at Iowa State College. She became a human computer. Her boss was George Snedecor.

Mary said math was her worst subject in high school. But she loved working with numbers and data. She mostly used punch cards for her work. She created formulas and checked the cards for mistakes.

The "Zero Check"

While working in Snedecor’s lab, Mary invented the “zero check.” This was a clever way to find errors. It was a sum that should always equal zero if all other numbers were correct. This helped her find mistakes in math problems.

Mary believed her lack of formal math training helped her. She noticed these sums that others, who were more trained, often missed.

Career Growth

By 1940, Mary Clem became a chief statistical clerk. She was in charge of the Computing Service. Later, in 1962, she moved to the new Computation Center at Iowa State University.

International Work

Mary also traveled for her work. In 1946, she went to Greece. She was a junior statistician and helped watch elections.

In 1952, she worked in Hiroshima, Japan. She was a statistical consultant for a group called the Atomic Bomb Casualty Commission. Her job was to help with data and statistics.