Fencer:
Fencer, Fencer....
1 GB = 1000 MB exactly!
It is the 1 GiB that it is 1024 MiB.

What is GiB? It's the so called gibibyte.
It is used to describe the actual memory storage.

For example all of you have hard drives that are advertised to be 200 GB, while when you go to your hard drive properties it is saying that they are only 186 GB. So what's happening? They have fooled us? No! It is just that the value we see from our computer via the properties of the hard drive is given in gibibytes(GiB) and not gigabytes(GB) ALTHOUGH it is incorrectly noted as GB. The correct unit should say GiB.
So a 200 GB hard drive says:
200·(1024^3)/(1000)^3 = 186 GB while it means GiB.