This is just common for other brand too, it is controversial, but practiced by all brand.

So basically they define as 1,000,000,000,000 bytes.
Devide by 1024, because 1 kilo byte = 1024 bytes
= 976562500 Kilo byte

Devide by 1024, because 1 Mega byte = 1024 Kilo bytes
= 953674 Mega byte
Devide by 1024, because 1 Giga byte = 1024 Mega bytes
= 931 Giga byte

They blame is Windows counting the byte in this way, that's why final calculation is 931 Giga bytes.
This apply for all the flash drive and memory card too.