Today is June 1101   but most would write it as June 13th, or Jun 13
                  2                                                 10

The subscript 2 in the 1101  indicates the base, which is base 2 or binary.
                           2

The subscript 10 after and below the 13 in June 13    indicates the base, 
                                                  10      base 10 or decimal.

1101 in base 2 is 1 8s plus 1 4s plus 0 2s plus 1 1s or 8 + 4 + 0 + 1 = 13

                      3        2          1         0
   1101     is   1 * 2  + 1 * 2   +  0 * 2   + 1 * 2

                   8    +   4     +    0     +   1     =  13 in base 10     

8543 in base 10 is:
                       3          2         1         0
                 8 * 10  +  5 * 10  + 4 * 10  + 3 * 10

                 8 1000s + 5 100s +  4 10s   + 3 1s    =  8,543 in base 10

You don't want to see what 8,543 looks like in binary.
It would have 14 binary digits!

Here is what 8,191 looks like:  1111111111111   8,191 is the largest possible
                                             2           13 digit binary
                                                                     number.
The above stuff should make more sense after you we use it for:

   1. setting the permissions for our web page files and folders
      and graphics, and

   2. specifying the colors of our web pages BGCOLOR (background color)
      and TEXT (foreground color), as well as LINK (hypertext) color.

We may even discover why Halloween is the same date as Christmas
for some programmers.  :-)

Base 10     Base 2    Base 8   Base 16  Base 10 Base 2
  0           0         0         0       0      0000
  1           1         1         1       1      0001
  2          10         2         2       2      0010  Base 16 = Hexadecimal
  3          11         3         3       3      0011  Base  8 = Octal
  4         100         4         4       4      0100  Base  2 = Binary
  5         101         5         5       5      0101  Base 10 = Decimal
  6         110         6         6       6      0110
  7         111         7         7       7      0111
  8        1000        10         8       8      1000
  9        1001        11         9       9      1001
 10        1010        12         A      10      1010
 11        1011        13         B      11      1011
 12        1100        14         C      12      1100
 13        1101        15         D      13      1101
 14        1110        16         E      14      1110
 15        1111        17         F      15      1111
 16       10000        20        10      16     10000
-------   -----     ------   -------  -------   ------
Base 10   Base 2    Base 8   Base 16  Base 10   Base 2