Name: Re: Visual Multiplication and 48/2(9+3)
Uploaded: 2020-03-30T03:09:47.000Z
Duration: 3 min 19 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

The comparative

While I'm working on some more ambitious projects,

Past simple

I wanted to quickly comment on a couple of mathy things

that have been floating around the internet, just

So there's this video that's been floating around

about how to multiply visually like this.

Then you start counting the intersections-- 1, 2,

3 on the left; 1, 2, 3, 4, 5, 6, 7 in the middle;

1, 2 on the right, put them together, 3, 7, 2.

But one of the delightful things about mathematics

is that there's often more than one way to solve a problem.

And sometimes these methods look entirely different,

And in this case, they're not so different at all.

Let me demonstrate this visual method again.

So we draw our nine lines and seven lines

Now, all we have to do is count the intersections-- 1,2, 3, 4,

How about instead of counting all the dots,

we just figure out how many intersections there are.

Let's see, there's seven going one way and six

Forget everything I ever said about learning

a certain amount of memorization in mathematics being useful,

Because apparently, I've been faking my way

through being a mathematician without having

And now I'm going to have to figure out 5 times 7, which

is half of 10 times 7, which is 70, so that's 35,

Wow, I really should have known that one.

OK, but the point is that this method breaks down

into four one-digit multiplication problems.

And if you do have your multiplication table memorized,

became the ones, tens, and hundreds place of the answer,

these do, too-- ones, tens, hundreds-- and you

Which is exactly the same kind of breaking down

into single-digit multiplication and adding

that you do during the old boring method.

The whole point is just to multiply every pair of digits,

make sure you've got the proper number of zeroes on the end,

But of course, seeing that what you're actually doing

is not something your teachers want you to realize,

or else you might remember the every combination concept

In the end, all of these methods of multiplication

into well-organized chunks, saying, well, 10 times 30

is this, 10 times 1 this, 30 times 2 is that, and 2 times 1

Add them all up, and you get the total area.

Don't let notation get in the way of your understanding.

Speaking of notation, this infuriating bit of nonsense

And that there has been so much discussion of it is sign

that we've been trained to care about notation way too much.

Do you multiply here first or divide here first?

The answer is that this is a badly formed sentence.

It's like saying, I would like some juice or water with ice.

Or do you mean that you'd like either juice with ice or water

and what's right and wrong, but really the burden

is on the author of the sentence to put in some commas

Mathematicians do this by adding parenthesis and avoiding

The mathematics is in what those marks represent.

You can make up any rules you want about stuff