Answer:
5 Million kilobytes = 5 GB
There are 1024 kilobytes in a megabyte. and 1024 megabytes in a gigabyte.
Technically 5000000 kilobytes exactly equals about 4.7498GB.
Also, 5GB exactly equals 5242880KB, which is greater than 5000000KB.
So if you where trying to partition a hard drive, and specified 5000000KB and expected to see 5GB, but found 4.74GB, this could explain why.
Note: Most formatting programs align partitions on a specific KB block, such as 4KB. A 5000000KB partition could be altered to be a different KB size.