Human body is made from around forty trillion cells

“The average human body is made from around forty trillion cells. Trillion! Forty trillion is 40,000,000,000,000. A truly impressive number. If we want your cells to be represented by individual people, then we need more than one hundred times as many people as have lived in the 250,000-year-long history of humanity. Let’s try to visualize this a bit. Right now around 7.8 billion people are alive. If we put them shoulder to shoulder, they surprisingly would only cover an area of around 700 square miles (1,800 square kilometers). Which is a little bit more than the surface area of London. To get forty trillion people we need to multiply this by 120”

Excerpt From: Dettmer, Philipp. “Immune : A Journey into the Mysterious System That Keeps You Alive”