1 GB = 1024 MB. This is what textbooks, exams and Windows use. Phone, pen drive and data pack companies take 1 GB = 1000 MB.

The company counts 1 GB = 1000 MB, but phones and computers count by 1024, and system files also take some space. So 128 GB shows as about 119 GB.

1 byte = 8 bits. Internet speed is usually given in bits (Mbps) and file size in bytes (MB).