A friend sent me a link to an intriguing youtube video demonstrating a visual method for multiplication used by the ancient Mayans.
But if you google ‘Mayan multiplication’, you also get a discussion of something called the “Russian peasant algorithm” a method of multiplying two numbers used by the ancient Egyptians and Romans as well as the Mayans.
You take the two numbers to be multiplied and write them beside each other
Then you double one and half the other, discarding any remainders as you halve them.
394 , 13146
You also have to cross out a line when the number on the halving side is even.
24, 210336 12, 420672 6, 841344
Finally, when the halving side has got down to one, you add the numbers on the doubling side that haven’t been crossed out, including the first number. The sum of these numbers is the product of the original two numbers.
Now doesn’t that just seem utterly absurd? And yet it works!