 Here's a way to do multiplication using doubling, halving and adding. To illustrate let's multiply 127 by 46 the old way. First we multiply by 6 and then by 40. We add the two together for the result. In this method we need two columns. Now pick one of the two numbers to be multiplied. We'll use the 46. Put it at the top of the first column. Divide it in half. If it were an odd number we'd subtract one to get an even number and then divide that in half. Continue this process until you get to the number one. Now place the other number, 127 in our example, at the top of the second column. Double it and double it again and again until you reach the row with the number one in the first column. Now scratch out each row that has an even number in the first column and add the remaining numbers in the second column. This is the product.