Convert from petagram to nanogram

Unit Definition (petagram)
The petagram is a metric unit of mass equal to 10E15 grams or 1 gigatonne (one billion metric tons). This unit is used in atmospheric science and other scientific contexts where large masses are considered.

Unit Definition (nanogram)
The nanogram is a metric unit of mass equal to 10E-9 gram, or one millionth of a milligram.