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Math Antics- Multiplying Fractions

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We will watch this video in class on 2/20 or 2/21

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you probably noticed that we've been talking an awful lot about fractions around here lately well now I'm going to tell you something you can do with fractions that you not juggling fractions it is pretty easy for me I'm talking about something even easier than that I'm talking about multiplying fractions multiplying fractions is super easy in fact it's easier than adding fractions and that's why we're going to learn it first the reason it's easier is because fractions are really just division problems and multiplication and division much better than addition and division Nelson's fractions are division that means if I have the problem 1/4 x 2/3 it's the same as the problem 1/4 x 2/3 that means I have both application and Division in the same problem and because they get along so well that means I can just rearrange our problem to look like this now it looks like two multiplication problems that are being divided and it looks just like a fraction in fact if we go ahead and do the multiplications 1 times 2 equals 2 and 4 times 3 equals 12 then we do have a fraction and it's the answer to our problem so what is all this me means that to multiply all you have to do is multiply the top numbers and then multiply the bottom numbers and today there's your answer as always let's see an example or two let's try this problem 2/3 x 4/5 rewrite the problem like we just saw but that's not necessary as long as we remember the procedure first we don't answer is going to be a fraction so let's go ahead and write a new fraction line for it next we multiply the top numbers 2 times 4 equals 8 so it's the top number of her answer and last we multiply the bottom numbers 3 times 5 equals 15 so 15 is the bottom number ever answer there we have it 2 / 3 * 4/5 equals 8 over 50 see how easy that was and fun to even funner than video games okay time for another example let's try 6 / 11 * 7 / 8 from a multiplication table 6 times 7 equals 42 so 42 is the top number of her answer and on the bottom we have 11 times 8 which is 88 so 6/11 times 7/8 equals 42 over 88 now some of you might see that this answer could be simplified but will save simplifying fractions for another video alright let's see one last example here it is 1/2 * 4 / 3 * 3 / 5 wait a minute this has three fractions multiplied together and the middle one looks like an improper fraction cuz its top numbers bigger than its bottom number is our procedure work for this problem to yep all we have to do is multiply all the top numbers together and then multiply all the bottom numbers together and we'll have our answer and this will work no matter how many fractions we have to multiply so on the top we have 1 * 4 is 4 and 4 * 3 is 12 + on the bottom two times 6 and 6 * 5 is 30 that means our answer is 12 / 30 so there you have it easy because fractions are just another way of writing division problems but remember there's another way to say stop fractions we can also use fractions to represent parts of things like half a pizza for instance but doesn't make sense to multiply half a pizza by another half actually it does if you're thinking of fractions as search of something then multiplying fractions is really like taking part of another part for example you can see that if I take one half of that half then I get 1/4 of a pizza and if we do multiplication 1/2 x 1/2 you see that we do get one for it so that's why you can think of multiplying fractions as taking part of another part in fact sometimes especially in word or story problems you'll see me applying fractions written using the word of instead of times they may ask what's 3/4 of 2/3 and now you know they just mean what's 3/4 * 2/3 so what do you think of fractions as parts of something or as division problems the procedure for doing the multiplication is exactly the same let's do a quick review of what we think it's easy order of operations says that we can do the multiplication before the division procedure for multiplying fractions does The X the top numbers to get the answers top number and multiply the bottom numbers to get the answers bottom number you think of fractions as parts of something then multiplying a fraction by another fraction is the same as taking a part of a part and sometimes especially in word problems you might see the word of instead of the word time even though multiplying fractions are so easy it's a good idea to practice so be sure to do the exercises and I'll see you next time learn more at Math Antics.

Uploaded by Lora Maslen.

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Math Antics- Multiplying Fractions

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