A prefix meaning one billion (1,000,000,000 or 109)
Examples:
• a gigagram is a billion grams
• a gigabyte is a billion bytes
• a gigameter is a billion meters (one million km), which is a little less then the diameter of the Sun.
Symbol is G
Example: 12 Gm = 12 gigameters = 12 billion meters (12,000,000,000 m)