1. When memory card manufacturers label storage capacity, they typically use the decimal system, where 1000M=1G; however, computer operating systems use the binary system, where 1024M=1G. This difference in calculation leads to a discrepancy between the actual usable space and the labeled space.
2. After partitioning and formatting, the operating system will occupy some space on the memory card to store system files.
In conclusion, the inconsistency between the displayed size and the stated size of the memory card is mostly caused by differences in binary calculations, space occupied by system files, and other reasons.