One of the oldest and most widespread use of counting and mathematics is the census.* The census is the official count of the people in a geographic area. The Constitution of the United States calls for a census to be taken every 10 years. Originally, the purpose of the census was to provide information for the periodical reapportionment of the House of Representatives. Today, census data is used for many reasons, including establishing where and how federal and state monies should be distributed.

*The census has its origins in the Roman Empire, but the modern system has its roots in seventeenth-century Sweden.

The U.S. Constitution requires its citizens to be "enumerated" or physically counted. But the precise meaning of the word "enumerate" has been debated in recent years. The beginning of the twenty-first century still sees census officials and researchers recommending different methods for estimating the number of...