Adding Left to Right
Date: 4/5/96 at 1:50:19 From: Sean Frances Aurora Devin Subject: MathMagic Hi- I am a parent of 5 children, 3 of whom are school-age. Because of my own math illiteracy, I have been reading out of a book titled _Math Magic_ by Scott Flansburg, "The Human Calculator". He teaches to add from left to right - the same direction we read - rather than the right to left method my children have been learning in school. I am having problems with some of his problems. Here are 2 problems that have me stumped: 8,703 2,961 + 343 and the other one: 9,272 5,498 27 2,309 8,565 In the first problem, I can't figure out what happens to the 9 left over from the 19 total after I carry the 10 to the thousands column. (Remember - we're doing this from left to right - try it.) In the second problem, I'm just totally confused. Will you please try these in this unique way and tell me how you do? The way I was taught in school where I add from right to left and carry is a breeze of course. Also, tell me if any of you math whizzes use this method, or are you familiar with it? What is your personal opinion? Thanks - MOM
Date: 4/29/96 at 21:36:41 From: Doctor Jodi Subject: Re: MathMagic Hi there! This is an intriguing idea. I'd forgotten how difficult "borrowing" and "carrying" could be. I have, upon occasion, added left to right in my head, but never before on paper, so this was an interesting experience for me. I think that adding in "columns" might make this easier for you. (It did for me!) Here's what I mean: I add the first column and write 24, then the second, and third, and last. 9272 5498 27 2309 8565 ------ 24 14 24 31 Do you see what I've done? Now I add the numbers that correspond to the same place value: 24 14 24 31 ----- 25671 Does this make sense? Try this for the first problem and see if it helps... You'll find that you'll have to "carry" once again, but I think it might be simpler if you can see what's going on. Good luck and let us know if you need more help... What do your kids think of this method? I think that it's really important to remember that there's no single "right" way to do math, so ideas like left-right addition are VERY important... -Doctor Jodi, The Math Forum
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