binario - base 2
  (32)    (16)    (8)     (4)     (2)     (1)
  2^5    2^4   2^3   2^2   2^1   2^0         decimal  - base 10
                                   1       0         1     =       5
                                   0       1         1     =       3
                                   1       1         1     =       7
                         1        1       0         1     =     13
                1       1        0       1         0     =     26
     0         1       1        1       1         0    =      30
     0         1       1        0       0         1    =      25
     0         0       1        1       0         1    =      13



   referencia 

  decimal                     binario
        0 ......................... 0 0 0 0
        1 ......................... 0 0 0 1
        2 ......................... 0 0 1 0
        3 ......................... 0 0 1 1
        4 ......................... 0 1 0 0
        5 ......................... 0 1 0 1
        6 ......................... 0 1 1 0
        7 ......................... 0 1 1 1
        8 ......................... 1 0 0 0
        9 ......................... 1 0 0 1
      10 ......................... 1 0 1 0
      11 ......................... 1 0 1 1
      12 ......................... 1 1 0 0
      13 ......................... 1 1 0 1
      14 ......................... 1 1 1 0
      15 ......................... 1 1 1 1

sumas

 decimal      binario 
   
    8     =        1000
+ 1     =         0001
=============
   9           


   dec                 bin
  1                   111
     5   ---         0101
+  5   ---         0101          
     2  ---          0010
=====================
   12                1100


   dec      bin
               101
     5 --    0101
+  5 --    0101
    5 --     0101
==========================
   15        1111