If digital data is stored in 0s & 1s, how does the reader know how many of the digits to take into consideration?

Question

Must be a very basic and dumb question. But ‘1001’ can be 9 and also 2 & 1 if ’10’ & ’01’ is taken seperately. I’m confused.

In: 49

Answer 1

The actual ELI5 answer: the same reason you understand 4803 as 4803 and not 48 and 3.

1. Separators: in this case, spaces or special sequences between words

2. Conventions: we use byte-sized words, so each 8 bits is a separate word

Of course, these have to be agreed upon by the sender and receiver.