A View from the Back of the Envelope top

Counting to ten billion...
on your fingers
Counting by powers of ten

If these are your hands... palms up and thumbs out... 

 ||||  |||| 
\||||  ||||/
 OOOO  OOOO 
  OO    OO
and these are a left-hand fist and right-hand finger & thumb... 

          | 
          |/
 OOOO  OOOO 
  OO    OO
then... 
       one
        100
             1 


    OOOO  OOOO
     OO    OO 
"ten to the zero"
       ten
        101
             10 

              /
    OOOO  OOOO
     OO    OO 
"ten to the one"
     hundred
       102
           100 
            |
            |/
   OOOO  OOOO
    OO    OO 
 "ten to the two"
     thousand
        103
           1000 
            ||
            ||/
    OOOO  OOOO
     OO    OO  
"ten to the three"
    ten thousand
        104
          10000 
           |||
           |||/
    OOOO  OOOO
     OO    OO 
"ten to the four"
 hundred thousand
       105
        100000 
         ||||
         ||||/
   OOOO  OOOO
    OO    OO 
"ten to the five"
      million
        106
      10  00000 
       |  ||||
       |  ||||/
    OOOO  OOOO
     OO    OO 
"ten to the six"
    ten million
        107
     100  00000 
      ||  ||||
      ||  ||||/
    OOOO  OOOO
     OO    OO 
"ten to the seven"
 hundred million
       108
   1000  00000 
    |||  ||||
    |||  ||||/
   OOOO  OOOO
    OO    OO 
"ten to the eight"
      billion
        109
   10000  00000 
    ||||  ||||
    ||||  ||||/
    OOOO  OOOO
     OO    OO 
"ten to the nine"
    ten billion
        1010
  100000  00000 
    ||||  ||||
   \||||  ||||/
    OOOO  OOOO
     OO    OO 
"ten to the ten"

Multiplication adds fingers, and division removes them.
So multiplying by ten adds a finger, and dividing by 1000 removes three.
So what is a hundred times a hundred?

I'm not sure this is truely of any use.

A View from the Back of the Envelope
Comments encouraged. - Mitchell N Charity <mcharity@lcs.mit.edu> 

History:
 1997.Jul.26  Layout upgrade.  Added disclaimer.
 1997.Jun.16  Added intro and changed finger-folded
              notation from O+ to just O.