How do people get a count for large gatherings such as the protest in Hong Kong, where it’s approximated that 2 million people are gathered

Question

How do people get a count for large gatherings such as the protest in Hong Kong, where it’s approximated that 2 million people are gathered

In: Mathematics

Answer 1

Herb Jacobs, Berkeley Journalism professor in the 60s came up with the method that is still used today, though refined. He had an office overlooking the quad, which was marked off in 10×10 grids. He counted people in grids during protests. People at arms length were 10 per grid, closer together, 20 per grid, etc.

[Here.](http://course1.winona.edu/eerrthum/math395/CapstoneReport2.pdf) Works best with an aerial view.