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Comment by zwieback | Hacker News Reader

Either way is fine, I think, if you the child understands the underlying mechanism. I'm the father of a 3rd and 5th grader in US public schools and I think the math curriculum is very good. However, sitting down and explaining basic arithmetic is important. I also teach them to estimate and come up with a quick upper and lower bound before they start the problem.

I went to school in Germany and our methods of multiplication and especially that of long division were a little different. When I first looked at the way long division is done in the US I thought it was confusing and my first reaction was that my method was better. It took a little time to overcome my cultural bias but I'm all better now.

Still waiting for the US to switch to Celsius and metric, though...

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I agree. For learning, the method shown is fine. Why? Because it teaches and honors place value, an extremely important concept in developing numeracy. I'm fine with any method that uses that.

I am not fine with something my kids call the "lattice method." The point of this method is simply to get the correct answer for multiplying large numbers. Is it clever? Yes. Does it work? Yes. But it does not teach math. If the educators' goal is simply to give a technique that works and gives the correct answer, teach them to use the calculator on their cell phones.

Lattice method for multiplication:

http://www.coolmath4kids.com/times-tables/times-tables-lesso...

I'm not sure why you think this lattice method does not teach place value. The page you linked to doesn't explain (at all) why it works, sure, but the method is just a clever way of notating place. I would expect any good teacher to get his or her students to understand that, and not just mindlessly fill in numbers.

I would expect any good teacher to get his or her students to understand that

That's not how I've seen it used. I've seen it used as a procedure for getting the answer. Compare that to the method shown in the npr link, first line: the numerals are 2 and 3, but the numbers multiplied 20 and 30. That's what I mean by teaching place value.

In the the old-school method I learned, we respected place-value by indenting (from the right), optionally writing the zeros.

"teach them to estimate"

I suspect that the 'calculator age' has caused kids (and kids that have now grown up to be parents) and maybe educators to over-value an increase in significant digits in calculations. It's interesting that the method of multiplication illustrated in the article is referred to as 'new' since when you use a slide rule, you operate in this way anyway. And to echo Hans Bethe, this is often "good enough".

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