### A good answer might be:

28 - 1 = 256 - 1 = 255. One of the 256 patterns (0000 0000) is used for zero.

# Largest Positive Integer in N Bits

The representation scheme we are looking at is called unsigned binary because no negative numbers are represented. Often when people say "binary number" this is what they mean. Here are some of its characteristics:

1. With N bits and base two representation, the integers 0, 1, 2, ... , 2N - 1 can be represented.
   - So, for instance, with 8 bits, the integers 0, 1, ..., 28 - 1 can be represented. This is 0 ... 255.
2. With N bits, zero is represented by 0....0....0 (all 0's).
3. (2N - 1) is represented by 1....1....1 (all 1's).

These facts are NOT always true for other representation schemes! Know what scheme is used before you decide what a pattern represents.

### QUESTION 6:

Without doing any calculation, which of the following is the decimal equivalent of 1111 1111 1111?

- 2048
- 4095
- 16384
- 18432

Look at fact 3 in the list and think a bit.

Hint: Actually, you should think about a bit.