Convert from avogram to gigatonne

Unit Definition (avogram)
The avogram is a unit of mass, equal to 1 gram divided by the Avogadro number.

Unit Definition (gigatonne)
The gigatonne is a metric unit of mass or weight equal to one billion metric tons (tonnes) or about 2.2046 trillion pounds. This very large unit is used, for example, in discussing the amounts of carbon added to the atmosphere by human activities.