suppose there is a computer with 18 bits address space and the cell size is 8 bits, then
What is the smallest and highest address?
smallest Address = 0x0000 (HEX)
highest address = 2^18 / 8
= 32768 = 0x8000 (HEX)
What will be the possible largest memory size of this computer in bytes, kilobytes and megabytes?
Memory Size = 2^18 X 8 bits
Memory Size = 262,144B (Bytes)
Memory Size = 262,144/1024 KB = 256 KB
Memory Size = 256/1024 MB = 0.25 MB
Note::
For more convenient representation the units KiB and MiB are used: in that Case The memory size is 2048KiB OR 2MiB