Not so many. Most people within the computer domain aren't even aware of all the details.
The slightly larger kilo unit actually have gotten it's own unit, or actually a set of units. 1024 bytes is one kibibyte, 1024 kibibyte is one mebibyte, and so on.
Even within the computer domain, both types of units are used. Disk storage manufacturers for example uses 1000 as kilo to measure disk sizes, while operating systems uses 1024 as kilo to measure disk usage. That means that a 2.0 terabyte disk only has room for 1.82 terabyte data. (Also, as some of the space is used to keep track of the data on the disk, the actual amount that you can store on the disk is even less.)
Even disk manufacturers aren't consistent, and both units has even been mixed to measure the size of a single type of disk. The (once) so well known 1.44 megabyte 3.25" floppy disk is actually neither 1.44 megabyte nor 1.44 mebibyte. It's actually 1.44 * 1000 * 1024 bytes, or 1.44 kilo-kibi-byte...