Russian Peasant method vs Ancient Egyptian method
The Russian Peasant method and the Ancient Egyptian method are related because they both employ the same fundamental mathematical concept of decomposing numbers into binary form and then using halving, doubling, and summation to perform multiplication. They are different interpretations of the same basic technique.
Edited
For example: Multiply 17 by 12 using the Russian peasant method
17 in binary is 10001 and 12 in binary is 1100.
Left Right
10001 1100
01000 11000
00100 110000
00010 1100000
00001 11000000
Now, cross out the rows where the number in the left column is even.
Left Right
10001 1100
00001 11000000
Finally, add up the numbers in the right column: 1100 + 11000000 = 11001100
If we convert this binary result back to decimal, we get 204. Therefore, 17 * 12 = 204
The connection to binary representation is evident in the halving process in the left column. By repeatedly halving the number, we are essentially breaking it down into its binary components. The doubling process in the right column corresponds to multiplying by powers of 2.
Hi Shawn, nice noticing of the half/doubling. I wonder if you might expand on your mention of binary. In what way?
ReplyDeleteHi Susan, l added one example to show the half/doubling in binary representation.
ReplyDeleteThanks for this interesting revision, Shawn!
ReplyDelete