Question

at the beginning of which century the world population was one billion​

Answer 1

Answer:

World population milestones went unnoticed until the 20th century, since there was no reliable data on global population dynamics. It is estimated that the population of the world reached one billion for the first time in 1804.

Answer 2

$\huge\underline\textbf{Answer}$

1804

It is estimated that the population of the world reached one billion for the first time in 1804.