Article: According to Milton Friedman, before the Industrial Revolution virtually all children worked in agriculture. During the Industrial Revolution many of these children moved from farm work to factory work. Over time, as real wages rose, parents became able to afford to send their children to school instead of work and as a result child labour declined, both before and after legislation. Austrian School economist Murray Rothbard said that British and American children of the pre- and post-Industrial Revolution lived and suffered in infinitely worse conditions where jobs were not available for them and went "voluntarily and gladly" to work in factories.

Question: How many children worked?
virtually all