Appropriate Representation of Numbers
Everyone agrees it is Africa's most populous nation. But what is its population? The United Nations says 114 million; the State Department, 120 million. The World Bank says 126.9 million, while the Central Intelligence Agency puts it at 126,635,626. What should bother you about this?
– Norimitsu Onishi, in a New York Times editorial titled "Consider Nigeria" from August 18, 2002.
Scientists have a convention for rounding numbers to the appropriate number of significant figures. In the age of calculators that mindlessly present many digits more than are significant, knowing how to round numbers "to the nearest tenth" or "to the nearest millionth" is essential.
In a lesson on Numbers and Their Application many topics related to the above topics are discussed.