I remember seeing a commercial a few years ago on an alternative way to add long lists of numbers, it had you adding from left to right so that you wouldn't have to carry, can someone explain how this is done and if it is easier?

Thanks!!!!

Never mind, I found it on a much earlier post in here, I still don't get it. Better stick to the conventional way!!!!!!!!

Well, I'd still like to try to answer your question, kittypal, and I can't find the earlier thread, so I'll try, anyway.

I've heard of this, too, and from what I can remember it works sort of like this. To keep the problem manageable, let's just add three numbers: 79+87+99. OK, add the first digits of each of these: 7+8+9 = 24. Write this down (or just keep track of it in your head). Now add the second digits, 9+7+9 = 25. Write this down under the 24, but move it one space to the right (thus placing the 2 under the 4 and the 5 alone at the right). Better yet, just imagine doing this, in your head. Add again and get 265, without carrying.

I think that with practice this kind of method would indeed be somewhat more efficient than the usual one. There are some complications I've left out, but I hope you get the picture. Actually, it's just a little trick. In writing the 25 down as shifted one space to the right, you're really doing the same thing as carrying the 2.

Here's probably a clearer way of presenting the alternative approach to addition, Kittypal.

Let's add 79 + 87 + 99 again. By starting on the left, what you're really doing is adding 70 + 80 + 90, and you can do that in your head, can't you? You get 240. Now add the units digits, 9 + 7 + 9, to get 25. Add 25 to 240 and you have 265, as before.

This method works because 79 + 87 + 99 is the same thing as 70+9 + 80+7 + 90+9, or, regrouping, 70+80+90+9+7+9. It works every time, too, and once you get use to it, it actually is faster, and you can very quickly learn to do it in your head.

Maiku, thanks again for clearing things up! It would be easier to have learned it that way, too bad I rarely do math problems. Might come in handy at the store!

Wow, that's so simple it's making me feel stupid for never having thought of it! What a neat trick!

I do math in my head all the time and have to stop and try to remember what I am carrying lol I'm going to work on learning this. Thanks for the explination, Maiku.