One hundred people is the ideal number between the economy and diseconomy of scale. More than one hundred and layers of hierarchy become an issue. Less and there's too much for each person to do.
By decentralising society into one hundred people strong self organising sharing communities with open-source internet and 3D printing, we can have a high-tech equal world with the scale necessary for efficient infrastructure, machinery, technology and specialisation of labour without money or any other authority.
For example, let's say two out of every 100 people want to build homes, but it's uneconomical to make the tools and machinery needed for just two people. So they get together with the two people who want to build homes from the 50 villages linked to their town, making 100 people.
This works well for our core needs but not for specialised things without an expanding circle of 100 people. Say one person out of 10,000 wants to use a large telescope. They connect with the nearest 100 people via the internet who want to use a large telescope to work out where and how to build one.
One hundred astronomers don't have the resources to build a large telescope, so each astronomer works with the glass/ceramic makers of their town who have their circle of 100 people and the engineers who have their circle of 100 and the computer-technician/software-developers who have theirs and the carpenter/plumber/electricians who have theirs.
A total of 40,000 people who can work on the project without the need for a hierarchy and the inevitable abuse of power that comes from having people in positions of authority.