How input gets stored in nasm when accepted it from user ?
This is not "nasm" problem, case.
Well, it seems you don't understand, what are you talking about.
Learn the interrupt, system function that you are using.
EDIT:
I have accepted 12 then what will be stored in [num1],[num1 + 1] & in [num1 + 2] ?
If you have accepted 12 digits (12 entered, keyboard key press), then,
[num1] should be the first digit that you entered,
[num2] should be the second digit that you entered.
If you want to input 12 numbers, you have to have a separate place for each number input.
It think, you will not, be able to input N numbers with a single system call, that would not be very smart.
You want to input N numbers? - Then call "single system call" N times and have those numbers (convert them, store them in buffer or else do what you like).
And, by the way, we don't input numbers!
We input and send keyboard strokes that are stored into buffer.
Input is usually terminated by ENTER or by buffer len.
Call 12x times, like this:
mov eax...
mov ebx...
mov ecx,num1
mov edx...
int 80h
mov eax...
mov ebx...
mov ecx,num2
mov edx...
int 80h
...
So, if you want to get a number from the input, you have to convert buffer, each digit, to a number.
EDIT:
mov eax...
mov ebx...
mov ecx,buffer
mov edx...
int 80h
If you input "HeLLo world",
after the input,
buffer content should be:
[buffer+0] = 'H'
[buffer+1] = 'e'
[buffer+2] = 'L'
[buffer+3] = 'L'
...
and so on.