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Video Transcript
Hi my name is Marija. I'm a mathematician and today I'm going to show you the lattice method of multiplication. So we're going to take a multiplication problem like 14 times 56 and instead of setting it up the traditional way, the 56 under the 14, we're going to set up lattice. So for lattice we're going to have to draw a square and we're going to go ahead and split that square into four equal parts and I'm going to write the first digit up top, 14, I'm going to split it up into its 10 digit and its 1 digit so it's 1, 4 and 56 is going to go ahead and go vertically this way, 56. Now you're going to have to draw a diagonal within each of the squares in your small squares. So I'm going to go like that, like that, like this and like this. Okay so I split each of my four smaller squares into half by splitting diagonals. Now I'm going to go ahead and multiply 1 times 5 and that product is going to go in this cube. Now what you do is 1 times 5 is 5 right? So it's going to go 0, 5 so you put the tens digit and then the ones digit but because they are is no tens digit here you just put a 0, 4 times 5 is 20 so I'm going to put the tens digit and the ones digit, 1 times 6 is 6 so it's just 0, 6, 4 times 6 is 24 so 24, tens digit, ones digit. Okay now when all of your multiplying within the square is done what we're going to do is some addition. You're going to add along the diagonals. So diagonals come this way right? So I'm going to add all the numbers going this way which is just the number 0 so obviously that's just going to be 0. Then I'm going to add 2, 5, and 0. I'm adding all the numbers along that diagonal, 2 plus 5 is 7, plus 0 is still 7. Now I'm going to add along this diagonal, 0 plus 2 plus 6 gives me 8. Along this diagonal is only this number so it's just 4. Now when you're done adding your solution is going to be read this way as an L. So we're going to start with the 0 which I don't need because as a leading number I don't need a 0, so I'm going to write 7, 8, 4. The product of 14 and 56 is 784. My name is Maria and I just showed you how to do the lattice method of multiplication.
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