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Math 7 - Module 2B - Lesson 13 Day 2

Added May 03, 2021 •

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Review how to Convert 1) Decimals to Fractions 2) Fractions to Decimal by rewriting Fractions with a Denominator with a Base of 10

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you better of you so the first thing we had was decimals to fractions let's do a quick review on that chiming in the chat if you know what we're doing when we get there so decimals two fractions quick review decimals to fractions the whole thing is the change a decimal to a fraction all we have to do is pretty much just look at the position of the decimal keep it simple let's go with keep it simple first look at how many spaces there are so in terms of the decimal places 123 so we got three decimal places first thing we could easily do is pretty much put down a one and for every single spaced you have put down a zero one space to space three spaces so it's over a thousand and then all you got to do is just put down the number of top. We don't need the 0 in front cuz you don't read it as zero 57 we would read it as just 57 so fifty thousand Sabaton we're just understanding simply another simple way is just to just know how to read it if you know how to read it and that's what that's forget were discount why are we Counting it's the name the position tense hundred thousand that's why it's over thousand whatever the number is over a thousand so some just got to be able to read it sometimes it helps it's even better if you know how to read it have to worry about this because a lot of guys why do I put it over this number why this why that if you understand why you can just do so let's go look at this one right here so poor so if you look at it you read this is a lot of us are lazy we read it as point 0 0 0 8 that's the lazy way get what you're saying but it's incorrect we read it as get rid of the zero placeholders we read it at 8 8 what you read it as a position tenth hundred thousands and thousands 8 and thousands infractions always need to be simplified so is this case right here eight ten-thousandths as a fraction always make sure you simplify your phone we could divide look at us both of these are even get / 2 8 / 2 that's for 10000 / 2 5000 I bet we can divide Again by 2/2 4 is 2 and then we could divide 5000 in half 2500 but we could divide it again / 2 2 / who is 1/2 of 2500 1250 so 1 and 121 1200 1000 that would be the final one so know how to read fraction know how to read s book reading the placement that is key and that's how simple writing a fraction give me a decimal as a fraction is you just got a place how many Place holders are there how many positions got to think so 17 HMR I'm just making something up one more so all you got to do is think what is this that's 1 million 789 600 E3 but position-wise we could ignore it as long as you know how to read it tenths hundreds thousands ten thousands hundred thousand million so all you got to do is write 10 million over 10 million but if you don't remember that just look at how many positions are in the decimal for the one and then all of you will represent US 1 2 3 4 5 7 0 1 2 3 4 5 6 7 and if you look at that right there and millions and millions and all you got to do is then rewrite this number as your numerator keep it simple don't have to do anything else I said so decimals to fractions something you got to know how to do and at the same time you have to simplify your fraction to once you're done writing it as a fraction it is an unsaid rule but it is a required rule so if right here 7 4057 thousand where is this right here a 10000 you would not give full credit you get partial credit you have to work your way all the way down here could you have skip some work yes you could have asked you / 8 8 / 8 right away that's the thing I didn't see it I just kept on dividing by what I could see decimals to fractions very easy and then let's go back and will do exercise to in their second right here size 2 was then fractions to decimals this is Method one tomorrow we're going to learn another method when you're stuck but for a lot of people this one's easy fractions to decimals by writing as a fraction Uber 10 ^ x some value of 1010 a hundred thousand ten thousand this is easy almost always but not always what do examples and forgive this so 3/4 we write it as something over a base of 10 that's what it's intended apart and that's an exponent to the next one 10 ^ 1 is 10 10 ^ 2 is 110 ^ 3 thousand so how we write this as something over thousand huge all we have to do is make an equivalent fraction so right here 3 / 4 I can become 100 by multiplying by 25 what you do when the denominator you do it a numerator you X the same thing noticed 25 over 25 as a value of one remote applying 3/4 by 1 Wenatchee in the way it's worth we're just changing the way it looks so if you multiply this look at this for * 25 it's over one hundred a hundred 3 * 25 is 25 so all you have to do to convert this into a decimal is just think all right we don't have a whole note that there's there's no hole number in front no mixed number no whole number so all it is we know it says 0 point something how many spaces go back to what we did backwards because this three decimal places we'd have three zeros right there 4 decimal places for zeros and then we have this was at 7 decimal places 7020 that means we got two decimal places all you need to do is fit that numerator into that spot right there so is 0-75 that fits in your two and you feeling from the back cuz you want to fill in so two spots to stop 75 7500 the 75 in the last place is a hundred you read it check your answer let's do something similar let's go 33/40 very similar but look at little bit of difference right here we have a 40 we want to change it to something of won't 40 * or nothing * 40 gets you a hundred so we got a game towards 1040 times what is 1000 same thing 25 so if we look at this 40 * 25 we get 1000 3 * 25 and so we got three decimal places for answer so 0 1 2 3 10 hundred thousands we got a thousand cover dinner small place but look at this what happens swego we got a zero point and we fill in the back we got to not we got a two digit number so it fills in the two spaces in the back are we have this x-ray here so that right there becomes a zero placeholder so 0.075 if we cover it up that's just the number 75 but position-wise tents thousand 75000 so notice I said fill in from the back we got two digits two spaces so fill in from the back don't go from the front that's only thing you have to worry about so too so let's go back to this right here this was our homework most guys did it and I think we did it in class when we did most of it so let's go right here so look at this right here that is an improper fraction we can actually simplify that right there two ways to do this one back she let's do this one down here first 35 / 50 35 over 50 with a x 2 / 251 is 50 * 2 is over 100 35 * 2 is 70 and then look at this right here how many spaces do we got we got to space zero point that and all we do is put this number in that space is 0.70 but a zero a placeholder in the back is growing back of the number we can actually drop off is 70 over 100 can be simplified by dividing by 10 7/10 * 7100 or 7/10 same thing so this lets us know is zero placeholder in the back and be dropped off for as a 0 placeholder in the front you got to keep I want to get this one right here two ways of doing this one we could leave it at 7:15 let's do that first * 20 / 20 cuz that gets us 140 over 100 Best Buy I don't know let's just look at it so we got two spots right there so we got zero point XX look at this we have a hundred and forty and two spots so that right there because it's here because it's an improper fraction we shouldn't have a service that's why I don't like this method either you got to know that's not a zero that's an end some number a whole number so we have a hundred and forty so it's 1.40 buttons attempt has one spot 14 restarting the back for 11.4 I don't like it like this but here look at another way let's get this let's simplify this fraction to a mixed number 1 + 2/5 alright so now we got this one because one point something that we got this 2/5 let's multiply that by my 10 by 2 cuz it comes up over 10 should we get one and four Pence so we get one decimal place one point and one decimal place and what number goes in the decimal place enumerator 1.4 safer to change it to a mixed number then leave it as an improper fraction so and then let's look at these right here 11/32 * to get something over which we have to go towards a hundred or a thousand 2 * so let's go look at some other things we could do let's do some work off to the side so 32 x what ends up being something over 1032 I'm going to go X 5 is why because five times to I get a zero I get a 10 and then right here I carry over that 160 and Savannah all right what do I multiply next I want to get rid of this 6th and make it a $0 * 5 Listen to Problem I hear 5 * 005 * 30 now becomes is there any carry over at 3 518 I got 800 now alright so now how do I change this 8in to attend I'm on my bike X to make 16 round cuz then I get another one 6 * 5 00 4000 Jack f4000 I can can I / 4 no it's not too big how do I make this four into 1000 * 2 if he comes auntie thousand times it by another five I'd guess 1 2 3 4 a hundred thousand so I had to make change 32 to a hundred thousand and what did I do to multiply that 5 * 5 * 5 x 5 x 5 1 2 3 4 5 5 ^ 5 is what I did let the next one right there a x 5 five times as what I'm saying the power of 5 5 ^ 5 oh that's why at The X 3125 that's pretty much what I did so that's why this method isn't all that great sometime sometimes it's easy like this easy ones to look at this right here we could still get it over something with bunch of zeros multiply that by 32 just a double-check 100000 * 11 C + 11 x 3125 3430 4375 and then how many decimal places one two three four five five decimal places and since there's no hole number it says 0 and then just put that number in here not all that fun see you got to think right here hey look at this 16 is half of 32 If I multiply it by 2 and that's why I sometimes work from other times he helped work right here it's recognizing that they're related Loosely but I can change this to 6/32 and for me now I see I can just * this number right here I know it's over a hundred thousand save myself a little bit of work and 6 then I just got to do that 6 x 3125 3125 * 6 30 carrier 3 was at 12 12 + 3 is 15017 what is at 18th so we got five decimal places and I got a 5 digit number 0. and we got this 0 in the back that's a placeholder you could cut that out Saudis right here there are times we can change it to something over 0 but not always so you

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Math 7 - Module 2B - Lesson 13 Day 2

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