Error message Insufficient free space in LVM

The error message Insufficient free space: 51200 extents needed, but only 51199 available needs to add a GB disk to LVM, the previous operation easily passed the error in lvextend-L + 200G/dev/localhost/root. The error message is as follows: Insufficient free space: 51200 extents needed, but only 51199 available www.2cto.com error indicates that only 51199 × 4Mib/1024 is available, and 51200 × 4Mib cannot be expanded. After calculation, the command lvextend-L + 51199G/dev/localhost/root is equivalent to 1024 GB. If no error is reported, the system prompts to execute the resized command Logical volume root successfully resized.