soroban

   3a
   _____________________________________
    |o o o o o o o o o o o o o o o | ||
    ||_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_o|
    || | | | | | | | | | | | | | o | o|
    |o o o o o o o o o o o o o o ...

Example with subtracting 128 from 237

1. Put 237 onto the soroban, then starting with the hundreds column: 2-1=1

   1a
   _____________________________________
    |o o o o o o o o o o o o o o o | |...

3. going to the hundreds column:  2-1=1
          -|
        _  _  __
         ) _)  /
        /_ _) /
          _   _
   ___  |  ) (_)
        | /_ (_)
      ___________
           _  _
        | | |...

Lesson 2 (from llizard's bbackwards sschool of soroban)

Example with subtracting 128 from 237

traditional method:

1. starting in the ones column:  7-8=9 (take one from the tens column...)

        ...

Adding 153 to 39 with the soroban:

1. Put 153 onto the soroban, then starting with the hundreds column: 1+0=1
(89 is less than 100 so zero is the number in the 100's column for it)
   _______________...

From llizard aka ejm:

Example with the numbers 153 and 39

traditional western method:

1. starting in the ones column:  3+9=12, carry the 1
           |
           _  _
        | |_  _)
        |  _...

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