How to Understand Extreme Numbers

The late statistics wizard Hans Rosling, who died this month at age 68,  brought at least 10 toilet paper rolls to some of his beloved presentations.  He would stack them into a tower on a table, each roll representing one billion people. In a 2012 talk at the Skoll World Forum, he used the rolls to show how, as the number of children in the world—2 billion—holds steady, the global population will rise from 7 billion to the (also indefinitely stable) figure of about 10 billion. “We are debating peak oil,” he remarked, “but we know that we have reached peak child.”

With his whimsical props and other colorful visualizations, Rosling was renowned as a translator between large, almost unfathomable numbers and the language of everyday experience. He understood that most of us need visualizations or analogies to mentally work with millions, billions, and other big powers of 10 that help define our world. They’re important for decisions that affect daily life, such as how money gets invested and which