What mass of CO2 have humans put into the atmosphere?

Wikipedia: Carbon dioxide [has] an average concentration of 385 ppm by volume or 582 ppm by mass. The mass of the Earths atmosphere is 5.14x10^18kg, so the total mass of carbon dioxide is 3.0x10^15kg (3,000 gigatonnes).

From various sources I know that pre-industrial CO2 was around 285 ppm by volume. The ratio won't change if I use volume rather than mass, so;

(100/385) X 3000 x 10^15 = 779 X 10^15kg.

If you read this, and no-one does, please correct the above in the comments

Cheers

Sam.