Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site umcp-cs.UUCP Path: utzoo!linus!philabs!seismo!rlgvax!cvl!umcp-cs!james From: james@umcp-cs.UUCP Newsgroups: net.math Subject: Re: Math for Smart Alecks Message-ID: <4908@umcp-cs.UUCP> Date: Sat, 28-Jan-84 18:00:23 EST Article-I.D.: umcp-cs.4908 Posted: Sat Jan 28 18:00:23 1984 Date-Received: Tue, 31-Jan-84 03:47:32 EST Organization: Univ. of Maryland, Computer Science Dept. Lines: 13 Yes, it works. Think of it this way: you start with two numbers, whose product you are going to construct. I'll call these numbers A and B. A*B is "A groups of B". If A is even, that is "A/2 groups of 2B", so you can see that anytime you halve the left number and double the right number, their product is equal to the product of the numbers immediately above them (in your columns). This means you should scratch out the numbers above them IN THIS CASE, WHEN the previous A was even! When the left number is odd, A * B == (A-1)/2 * 2B + B, so you need that extra B immediately above the new 2B in the DOUBLES column, to allow for the remainder you ignored when halving A. --Jim