Manufacturers shows the size with 1000 bytes being a Kilo Byte when it is in fact 1024. Carry that through and your 320GB drive is in fact 298.
The math is 320,000,000,000,000 /1024/1024/1024 = 298
Surface Pro (2017) vs Surface Pro 4
Where HTML5 is headed next
MacBook Pro v Surface Pro 5
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