Example:
15 meter per UK gallon = 3.299532e-9 Gm/L
1 meter per UK gallon = 2.199688e-10 Gm/L | 1 Gm/L = 4.546099e+9 meter per UK gallon
Conversion Steps:
15 × (0.219968799 / 1e+9) = 3.299532e-9