General - 250GB = 233GB

Hard Disk Manufacturer

1GB = 1000 MB; 1 MB = 1000 KB
250 x 1000 x 1000 x 1000 = 250000000000 Bytes = 250 GB

Computer

1KB = 1024 Bytes
250000000000/­ (1024*1024*1024) = 232.83 GB