Possibly, but that claim is false. On the 64GB Surface Pro, the fraction should be 1/2, if the calculation is done in decimal (billions of) bytes.
As with the MacBook Air and other systems, the 64GB or 128GB (decimal) that is advertised only comes to 59GB or 119GB of real (binary) space.
If you are still naive enough to think that buying a 128GB PC or drive gets you 128GB of usable binary file space then your calculation cannot possibly be correct.
Note, I'm not saying that 1/2 is good, merely that 1/3 is wrong.
As with the MacBook Air and other systems, the 64GB or 128GB (decimal) that is advertised only comes to 59GB or 119GB of real (binary) space.
If you are still naive enough to think that buying a 128GB PC or drive gets you 128GB of usable binary file space then your calculation cannot possibly be correct.
Note, I'm not saying that 1/2 is good, merely that 1/3 is wrong.