Peasant Multiplication

The so-called (Russian) Peasant Multiplication is an acient method to multiply two numbers without the need to memorize multiplication tables or to use positional notation. It can be performed using a few pits in the ground and a number of stones or other items. Each single step can be performed mechanically without any real "computational skills".

First, in the holes below the first factor, you repeatedly put half as many stones as in the previous one until you only have one left. If the number of stones in a pit is odd, just ignore the remainder.

Then, in the holes below the second factor, you repeatedly put twice as many stones as in the previous one until you have filled as many holes as on the left side.

Then, for all holes on the left side which hold an even number of stones (marked with a blue color above) empty their neighboring pit to the right.

Finally, you put all remaining stones of the right side into one pit. The number of stones in this pit is the product of the two factors.
 
Copyright (c) 2016, Prof. Dr. Edmund Weitz.