1 kilobyte é na verdade 1024 bytes. Então
500,000,000,000 / (1024*1024*1024) = 465.66 GB
To a hard disk manufacturer, one KB is 1000 bytes, one MB is 1000 KB, and one GB is 1000 MB. Essentially, if a hard disk is advertised as 500GB, it contains 500 * 1000 * 1000 * 1000 = 500,000,000,000 bytes of space.
However, manufacturers of RAM don’t sell it in even groups of 1000 – they use groups of 1024. When you’re buying memory, a KB is 1024 bytes, a MB is 1024 KB, and a GB is 1024 MB.
Unfortunately, Windows has always calculated hard drives as powers of 1024 while hard drive manufacturers use powers of 1000.