A viral video circulating online claims the population of China is actually a billion people lower than the UN and China say.
A billion is big number, you'd think the Chinese would notice if that many were missing - and the claim is certainly false.
However, as the team dug into the stats, a strange story emerged - which suggests the official data on births and fertility may not be quite as reliable as you might think.
We spoke to demographer Professor Sabu Padmadas from the University of Southampton to find out more.
If you spot a story you'd like us to dig into contact us at moreorless@bbc.co.uk
Presenter: Tim Harford Reporter: Lizzy McNeill Series Producer: Tom Colls Editor: Richard Vadon Sound Mix: James Beard