The Way You Learned Math Is So Old School
1–10 of 28 posts
Re: The Way You Learned Math Is So Old School
#2Geez, there are so many things wrong with this article, all I could do was scream "shut up" in my head.
The only thing worse than math education in the US is the pop culture-media surrounding it.
Re: The Way You Learned Math Is So Old School
#3Surely that method of multiplication is not suited for larger numbers, to get 246 * 369 u do
200 * 300
200 * 60
200 * 9
40 * 300
40 * 60
40 * 9
6 * 300
6 * 60
6 * 9
So for x-digit multiplied by y-digit u need to write down x*y products and then sum it up, where as for the old method you need to only write down min(x,y) products and sum it up.
Re: The Way You Learned Math Is So Old School
#4The way the article shows is essentially calculating:
(30 + 6) * (20 + 4)
Which is great and all, but I think it would make more sense to do this:
(24 * 6) * 1 + (24 * 3) * 10
This is a lot closer to how machines actually do multiplication, so if the goal is to conceptually understand multiplication so you can have a computer do it, that makes more sense to me.
Plus it's easier to do in your head that way.
Re: The Way You Learned Math Is So Old School
#5...Does anyone actually teach their kids with that retarded method? All it does it take up more space, and shift the burden from screwing up carries while multiplying to screwing up carries while adding.
And since it's so brain dead to implement, I can't see any significant amount of kids even reflecting on how 'the numbers work' based on that.
Re: The Way You Learned Math Is So Old School
#6In my head I would do:
30 * 24 (which is just 3 * 24 * 10) = 720 6 * 24 (which is the same as 12 * 12) = 144 720 + 144 = 864
Re: The Way You Learned Math Is So Old School
#7At risk to be downvoted to death, I have to say that the new way of multiplication is actually _better_ than the old one, at least for kids starting to learn how to multiply.
All the new multiplication algorithm does is makes implicit additions explicit, so that you do not have to keep carry-over digit in memory. 144 is 120+24 and 720 is 600+120. Sure it trains your short memory, but we are talking about 7yr olds here. Once kid feels comfortable s/he will naturally move to the "old" way of multiplication.
And anyway... It is easy to nitpick on something we understand very well, but how about the topic? What would you do to make math more enjoyable in the classroom? I know what worked for me personally and that was not classroom drilling of multiplication, divisions, and stupid problems with two pipes filling the pool at different speeds.
What made me love math are Marin Gardner's books and other fun math books. It was much more interesting to solve crimes with what I later came to know as propositional logic, or cutting tori in different ways.
Re: The Way You Learned Math Is So Old School
#8The way the article shows is essentially calculating: (30 + 6) * (20 + 4) Which is great and all, but I think it would make more sense to do this: (24 * 6) * 1 + (24 * 3) * 10 This is a lot closer to how machines actually do multiplication, so if the goal is to conceptually understand multiplication so you can have a computer do it, that makes more sense to me. Plus it's easier to do in your head that way.
My inclination would be to be much less computer like about it. First start with some observations about the numbers. 24 is one less than 25. 4 * 25 is 100. 36 is 9 * 4. Therefor the answer is (9 * 100)-36=864. Numbers have properties. You can use these properties to do less mental work or at least take up less mental temp space. Not sure how you teach people to do that.
Re: The Way You Learned Math Is So Old School
#9...Does anyone actually teach their kids with that retarded method? All it does it take up more space, and shift the burden from screwing up carries while multiplying to screwing up carries while adding. And since it's so brain dead to implement, I can't see any significant amount of kids even reflecting on how 'the numbers work' based on that.
I think the argument is based around getting kids to realize that numbers are not monolithic things to put where X goes. They can be broken up and dealt with in multiple ways.
FWIW, I routinely find people who can't do simple single-times-double digit multiplications in their head, simply because it never occurs to them that they can turn 7 * 12 into (7 * 10) + (7 * 2), or 7 * 3 (=21) * 4 (4x2=8,4x1=4, =84). I figured out how to do so myself, school never taught it to me, and I seriously doubt more than a 5% left my high school knowing how to do this, much less actually using it.
Re: The Way You Learned Math Is So Old School
#10After watching a video on Khan Academy on Lattice Multiplication, I assumed that it was the "new way" of doing multiplication by hand.
I certainly would use lattice multiplication in preference to traditional long multiplication methods if I ever had to multiply large numbers by hand. I wouldn't be able to say which method is better for a 7 year old learning the concepts though.