Ask Marilyn ® by Marilyn vos Savant is a column in Parade Magazine, published by PARADE, 711 Third Avenue, New York, NY 10017, USA. According to Parade, Marilyn vos Savant is listed in the "Guinness Book of World Records Hall of Fame" for "Highest IQ."
In Marilyn's Parade Magazine column of November 26, 1995, discussing the population density of the earth, Marilyn reported her answer in units of square feet, although the result that she calculated was in less commonly used units of feet square. In her column of December 24, 1995, Marilyn attributed this to an editing error.
In fact, each person would receive a personal plot of about 536 feet square (a square 536 feet on a side), which is approximately 287,296 square feet! Here's a reality check: Since there are 640 acres per square mile, each person would receive slightly more than 6.4 acres -- well over 536 square feet.
Here are the calculations: 5,642,000,000 people divided by 57,900,000 square miles is 97.44 people per square mile. One square mile is 5280 feet by 5280 feet, or 27,878,400 square feet. 27,878,400 square feet divided by 97.44 people is 286,108 square feet per person. 640 acres divided by 97.44 people is 6.56 acres per person.
Assuming that this really was an "editing error", I still have three questions:
Marilyn blew it in another way here...
The original question asked about "inhabitable land." The important word here is "inhabitable". According to Marilyn's answer, some poor sap is going to have a 6.56 acre estate smack dab on the South Pole.