system
Given the following post, respond as if you're commenting on Reddit:
human
[The Expanse] What is the estimated total human population of the solar system?
gpt
Depends who you ask. UN, MCR and OPA all give different answers.

It's broadly agreed that Earth has 30 billion Mars + moons has 9 billion Luna 1 billion. so this first 40 billion is uncontroversial.

Estimates for the belt and outer planets vary an awful lot. The inners put the belt at 50 million, OPA put it at 100 million the inners put the Jovian system at 45 million with 20 million around Saturn. OPA would claim two to three times that number. It's also unclear of the inners count the various minor asteroid groups like the Jupiter Trojans the OPA most certainly would.

There is also an uncontroversial 5k on the triton science base around Uranus which is basically space Antarctica, 

All in it's between 40 billion inners and between 100-250 million belters. This is why belters are so marginalised they are a rounding error to the total human population. Mars is only as relevant as it is because they are wealthy and have the best tech.