Exa-

A prefix meaning one quintillion (1,000,000,000,000,000,000 or 10¹⁸)

The same as multiplying by 10¹⁸

Example: our Milky Way Galaxy is about an exameter wide

Symbol is E

Example: 12 Em = 12 exameters = 12 quintillion meters (12,000,000,000,000,000,000 m)