Convert from clove to petagram

Unit Definition (clove)
The clove is an old English unit of weight. A clove is usually considered equal to 1/2 stone or 1/16 hundredweight; that's 7 pounds (3.175 kilograms) by the modern definition of the stone, but in the past the clove varied from 6.25 to 8 pounds.

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.