2 1 0 
1 7 5
     10
	 
5 ykkösiä
7 kymmeniä          2        1        0
1 satoja        1*10   + 7*10   + 5*10

3210          3       2      1      0
1010 =     1*2   + 0*2  + 1*2  + 0*2  = 1*8 + 0*4 + 1*2 + 0*1 = 10;
    2
	
1	
2 6	3 1
8 4 2 6 8 4 2 1 
1 0 1 0 1 0 1 1   = 128 + 32 + 8 + 2 + 1 = ...

                       4    5    6    5     9   C
 0000  =  0           0100 0101 0110 0101 1001 1100
 0001  =  1
 0010  =  2
 0011  =  3           32  = 0011 0010
 0100  =  4           41  = 0100 0001
 0101  =  5           42  = 0100 0010
 0110  =  6           43  = 0100 0011
 0111  =  7           61  = 0110 0001
 1000  =  8           62  = 0110 0010
 1001  =  9 
 1010  =  A
 1011  =  B 
 1100  =  C
 1101  =  D
 1110  =  E
 1111  =  F


 21      = 
   10
   
   
 21/2    = 10  1/2    -> 1
 10/2    =  5  0/2    -> 0
  5/2    =  2  1/2    -> 1
  2/2    =  1  0/2    -> 0
  1/2    =  0  1/2    -> 1

 10101 = 16 + 4 + 1 = 21
 
 1 0 1 0 1
 16 + 4 + 1 = 21