I read the guide before and forgot what it's all covering but I just want to add:
when you get to 2^10 as in 1024, afterwards you just go 1K, 2K, 4K, 8K, 16K and it's same thing basically.
Therefore 2^20 is just 1K * 1K = 1MB
And 2^16 is same as 1K * 2^6 which is 64 equalling 64KB