Yep, this is why. People understandably get confused all the time about this. Redditor geoldr posted as straightforward of an example explaining that it's not as simple as multiplying by 10 as I could find:
"Basically you need to start calculating from bytes not gigabytes.
500GB is 500,000 MB. 500,000 MB is 500,000,000 KB. 500,000,000 KB is 500,000,000,000 Bytes.
Just dividing by a 1000 you see?
But in reality, 1MB is NOT 1000 KB. It is 1024 KB.
So you take the value 500,000,000,000 and divide it by 1024 three times to get from bytes -> kilobytes. from kilobytes -> megabytes. and megabyte -> gigabyte.
And you get 465 GB." /r/geoldr