As of 2018, the US GDP is 7.34x the one of France, not 10x. And in 2019, the US population is 4.91x bigger that France population, leading to a GDP per capita being 1.50x higher, not 2x.
You cannot round numbers at 1 significant digit and use them for further computations, that's butchering math.
You cannot round numbers at 1 significant digit and use them for further computations, that's butchering math.