Arithmetic (all content)
- Using area model and properties to multiply
- Multiply 2-digits by 1-digit with distributive property
- Multiplying with distributive property
- Multiplying with area model: 6 x 7981
- Multiplying with area model: 78 x 65
- Multiply 2-digit numbers with area models
- Lattice multiplication
- Why lattice multiplication works
Sal introduces lattice multiplication. Created by Sal Khan.
Want to join the conversation?
- Well I see the trick you did there Sal but how does the lattis multiplication work? I mean what is the meaning of lattice multiplication if you don't know how it works. Your the BEST Sal.(107 votes)
- The next video does explain it but here's a brief overview. Each diagonal represents a place value (ones, tens, hundreds, thousands.) Because you have to recognize that there are zeroes at the end adding place value, the place value of the answer goes up, too. (4x3 is obviously more than 40x30.)(61 votes)
- Since this is lattice multiplication, (another way to solve a multiplication problem), is there a way to solve a division problem another way like multiplication? I am very curious.(56 votes)
- I know that this introduction into Lattice Multiplication is meant to show us that there are numerous ways to approach different functions within mathematics, but is lattice multiplication used in or in any way required for completing higher aspects of math such as calculus, trigonometry, etc.? I would just like to know because although I appreciate how interesting it is, I don't really feel like investing the time in watching the videos and practicing it unless it ends up being a basis for higher maths. Thanks in advance for any responses!(16 votes)
- i guess it is just a curious method to do multiplication. i'm from Portugal and i didn't even knew this method until i saw the video.
but i think this isn't going to be useful to you in higher maths, as you'll be using a calculator for advanced problems.
but you really should learn it! it is a fun and easy way to multiply, and you get to teach it to your friends too =))
knowledge is power(18 votes)
- What does lattice translate to? What does it mean?(8 votes)
- The grammatical definition of lattice is:
1. A structure consisting of strips of wood or metal crossed and fastened together with square or diamond-shaped spaces left between.
2. An interlaced structure or pattern resembling grating, grids, grilles, or grates.(7 votes)
- where does the word lattice come from?(7 votes)
- You've probably seen a "lattice" before. It's basically a decorative wall, or fence if you will, made by criss-crossing some materials, usually wood, diagonally across each other. The diagonal lines, or lattices, Sal made are what give this method of multiplication its name!(1 vote)
- How do I recommend this video to all of my students?(3 votes)
- This question may have already been asked somewhere, (I don't know for sure) but what does lattice mean?(3 votes)
- A structure consisting of strips of wood or metal crossed and fastened together with square or diamond-shaped spaces left between, used typically as a screen or fence or as a support for climbing plants or Lattice multiplication, also known as gelosia multiplication, sieve multiplication, shabakh, Venetian squares, or the Hindu lattice, is a method of multiplication that uses a lattice to multiply two multi-digit numbers. It is algorithmically the same as regular long multiplication, but it breaks the process into smaller steps, which some practitioners find easier to use.(2 votes)
- What is Lattice?(2 votes)
- what does lattice mean?(1 vote)
- In mathematics, a lattice is a partially ordered set in which every two elements have a supremum (also called a least upper bound or join) and an infimum (also called a greatest lower bound or meet). An example is given by the natural numbers, partially ordered by divisibility, for which the supremum is the least common multiple and the infimum is the greatest common divisor.(5 votes)
I'm going to do a couple of lattice multiplication examples in this video. And in the next one we'll try to understand why it worked. Let's say we're trying to multiply 27 times 48. What you do is you write down your 27. The 2 and the 7 are going to get separate columns and you write your 48 down the right-hand side, and then you draw a lattice. This is why it's called lattice multiplication. So the 2 is going to get its own column. The 7 is going to get its own column. The 4 is going to get its own row and the 8 is going to get its own row. Now the fun thing about lattice multiplication is you get to do all of your multiplication at one time and then you can finish up the problem with all your addition. You don't have to keep switching gears by carrying and all of that. Although there is carrying, but it's all while you're doing the addition step. So we're almost done with our lattice. We actually have to draw these diagonals here. We'll understand in the next video why these diagonals even work. Just like that. And now we're ready to multiply. 7 times 4 is 28. 7 times 4 is equal to 28. So you write down a 2 and an 8 just like that. 2 times 4 is equal to 8. So you write down a 0, 8 just like that. Then you have 7 times 8. 7 times 8 is equal to 56. So we write down a 5 and a 6. And then finally, 2 times 8 is equal to 16. You write down a 1 and a 6 just like that. And we're done all of our multiplying. Now we're ready to add. So what you do is you go down these diagonals that I drew here. So this first diagonal, which is really the 1's diagonal, you just have a 6 sitting here. So you write a 6 just like that. Then we move over to the next diagonal. This diagonal with the 6, 5, and 8 in it. That's our 10's diagonal. So 8 plus 5 is 13. 13 plus 6 is 19. So you write your 9 right here in the 10's place and now you carry the 1 in 19 up there into the 100's place because this isn't just 19, it's actually 190. It's nineteen 10's. Anyway, you carry your 1. You have 1 plus 2 is 3. 3 plus 8 is 11. 11 plus 1 is 12. You write the 2 in your 100's place and you carry the 1 into your 1,000's place. 1 plus 0 is 1, so you just have a 1 in your 1,000's place just like that. And you get our answer. 27 times 48 is equal to 1,296/ Let's do a harder problem. One that requires more digits, just to show that this'll work for any problem. Let's say we had 5,479 times-- let's do a three-digit number. Times 787. So just like we did in the last time, we make four columns. One for the 5, the 4, the 7, and the 9. We'lll have 5,479 and then times 787. So they each get their own row. 787. Looks like that. Then we have to draw our lattice. Draw the lattice. Each of these guys get their own column. Draw the columns just like that. And then each one of these characters got their own row. One row for the 7, one row for the 8, and one row for this other 7. Then we have to draw the diagonals. Draw it like that. One diagonal, two diagonals, so three diagonals, four diagonals. I think you get the idea and than we have just one, two more diagonals. We're ready to multiply now. So it's 9 times 7. I won't do it on the side here. We know our times tables. 9 times 7 is 63. 7 times 7 is 49. 4 times 7 is 28. 5 times 7 is 35. Let me switch callers arbitrarily. 9 times 8 is 72. 7 times 8 is 56. 4 times 8 is 32. 5 times 8 is 40. I'll switch colors again. 9 times 7-- we saw that before. It's 63. 7 times 7 is 49. 4 times 7 is 28. And then 5 times 7 is 35. We're done all of our multiplying. Now we can switch our brains into addition mode. Let me find a nice suitable color for addition. Maybe a pink will do for addition. So we start at our 1's place. Just have a 3 there, so you write the 3 in your 1's place. You go to the 10's place. 2 plus 6 is 8. 8 plus 9 is 17. Write the 7 in the 10's place, carry the 1 into the 100's place. I wrote a 1 really small here. 1 plus 3 is 4. 4 plus 7 is 11. 11 plus 6 is 17. 17 plus 4 is 21. 21 plus 8 is 29. Write the 9 in the 100's place and carry the 2. 2 plus 6 is 8. 8 plus 9 is 17. 17 plus 5 is 22. 22 plus 2 is 24. 24 plus 2 is 26. 26 plus 5 is 31. Carry the 3. 3 plus 4 is 7. 7 plus 8 is 15. 15 plus 3 is 18. 18 plus 0 is 18. 18 plus 3 is 21. Write the 1, carry the 2. 2 plus 2 is 4. 4 plus 5 is 9. 9 plus 4 is 13. Write the 3, carry the 1. 1 plus 3 is 4. And we're done. That easy. Well, there's two advantages here. One is we got to do all of our multiplication at once. And then we got to do all of our addition at once. The other advantage is it's kind of neat and clean. When you just do it the traditional way with carrying and number places, it takes up a lot of space. But notice, we did our whole problem in a nice, neat and clean area like that and we got our answer. Our answer is 4,311,973. There you go. Now in the next video we're going to try to understand why this worked.