In the binary number system, numbers are referred to as bits. What happens every time you add a bit

Adding another bit to a binary number will expand the maximum value that can be represented by that number by a power of 2.  Examples: 1111 can store 15 in decimal, while 11111 can store 31 in decimal.

Adding a bit to a binary number is exactly the same as adding a "place" to a binary number and will expand the range of values that can be represented by an order of magnitude.

Explanation:

A single bit can only be used to represent 1 or 0.  But if you add a second bit, you can now represent numbers up to 3.  Each new binary digit added to a binary number adds another power of 2 (binary is based on 2 states, on/off or 1 and 0) at that position.  Look at this comparison of digits and their associated maximum number between a binary (base 2 number) vs. a decimal  number (base 10 numbers that you use every day).

Digits        Max Binary        Max Decimal

1                1                         1

2               11 (3)                  99

3               111 (7)                 999

4               1111 (15)              9,999

5               11111 (31)             99,999

6               111111 (63)           999,999

7               1111111 (127)         9,999,999

8               11111111 (255)      99,999,999

As you can see, each time we add a new digit in binary we expand the maximum number by 2x (actually 2x-1).  When we add another digit to a decimal number we expand the maximum number by 10x (actually 10x-1).