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### Course: Math for fun and glory>Unit 1

Lesson 9: Other cool stuff

# Re: Visual multiplication and 48/2(9+3)

A quick response to some mathy things going around. Created by Vi Hart.

## Want to join the conversation?

• Did anyone see Vi Hart draw the dolphin at above the 42? Anyone get the reference?
• In the Hitchhikers Guide to the Galexy series, some scientists built a giant computer to calculate the answer to life the universe and everything. The computer says that the answer is 42. This doesn't make sense, so the scientests then wanted to know the question to life the universe and everything, so they made another giant computer. This computer was the earth. The dolphins and the mice were the only creatures on the planet that knew it was a giant computer.
• What are binomials?
• A binomial is a polynomial with 2 terms. In other words, a binomial is a polynomial with two smaller monomials inside it that are numbers or numbers multiplied by variables.
(1 vote)
• Is this visual way of multiplication the same as how latice multiplication works?
• In a way, yes. In lattice, you multiply the place values and add up the numbers. It turns out that what should be the hundreds' places of the products end up being the hundreds' places in your answer. This is pretty much that, but with lines. That makes it close to lattice, but it's closer to the rectangular methods way of multiplying, where you split up a big rectangle into smaller ones.
• Dumb question, but with the visual multiplication wouldn't you get the same answer for something like 31*12 as you would for 13*12, as you still are drawing the same amount of lines?
• No, because the order of the line sets is important. Drawing 3 lines, then 1 is not the same as drawing 1 line, then 3
• at 0:7,when Vi Hart says,"So there is this video floating around", what is the video called?
• There are quite a few videos floating around by now, demonstrating how to multiply using crossing lines. Here's one I saw: http://youtu.be/sd_Bub5jEJY
You can search for them using words "multiplication" and "lines"
• How does she find the area of that? It's BLOWIN' MY MIND!
• She's just finding the area of different parts of it and adding them all together.
Say you have something that is 17x3. You know that 15x3 is 45, and that 2x3 is 6. so, you can just add them together instead of trying to find 17x3. (Proof of this is that 17x3 = (15+2)x3, and since you normally would just do the parentheses first, you can distribute and then add.
It makes a lot easier to find the area of huge things, like calculating the squares on a tile floor. (Which yes, I have done)
• Its quite complicated can someone help me?
• Hola somos el eln les informaremos qye iremos atodo estado unido y alos estedos islamicos a si que dejen de jugr mamahyevos
• how do you answer this question its quite puzzling
3 (6 + 3 ÷ 3 ) +2
(1 vote)
• How come everyone thinks that 48 / 2(9 + 3) is dumb? I'm no math genius, but this is how you'd solve it.
48 / 2(9 + 3)
48 / 2 * 12
24 * 12
288.
Did everyone just suddenly forget the order of operations?