Wasn't sure at first, but then noticed the drive was NTFS
The 0.29 GB missing is used for the MFT. (Master Filing Table) On NTFS volumes Windows uses the MFT as a place to record what's in each sector on the drive, I think, like the File Allocation Table on FAT volumes. The difference with NTFS and FAT / FAT32 is Windows reserves x amount of space for it with NTFS, varying depending on how big the volume is.
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