Because it is not possible.

"Computers, on the other hand, think in base 2 (each bit is either on or off, only two states). While we like to group things in powers of 10, computers feel most comfortable grouping things in powers of 2. If a computer were to group boxes together, it'd be in groups like 1 (20 ), 2 (21 ), 4 (22 ), 8 (23 ), ... , 256 (28 ), 512 (29 ), 1024 (210 ), 2048 (211 ), etc. Those numbers just make "sense" to the computer just like how 100, 1000, etc just make "sense" to humans, and it allows the computer to access and use all of that memory in efficient ways and keep track of all of it easily."

If you want to read more about this: https://www.reddit.com/r/explainlikeimfive/comments/jcsqg/why_does_ram_come_in_specific_sizes_256_512_1024/