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Thời điểm hiện tại:0:00Tổng thời gian:10:07

never hurts to get a lot of practice so in this video I'm just gonna do a bunch more of essentially what we call long division problems and so if you have four goes into two thousand two hundred and ninety two and I don't know why exactly why they call it long division and we were we saw this in the last video a little bit I didn't call it long division then but I think the reason why is you could think it takes you a long time or it takes a it takes a long piece of your paper or you kind of as you go along you kind of have this thing that gave me this long tail that develops on the problem so all of those are at least reasons in my head why it's called long division but we saw in the last video that it's a way to tackle any division problem while just knowing your multiplication tables up to maybe ten times ten or twelve times twelve and just as a bit of review this is the same thing as two thousand two hundred and ninety two divided by four and it's actually the same thing you probably haven't seen this notation before as two thousand two hundred and ninety two divided by four these this this and this are all equivalent statements on some level and as you can see you say hey Sal that looks like a fraction in case you have seen fractions already and that is exactly what it is it is a fraction but anyway I'll just focus on this format and in future videos we'll think about other ways to represent division so let's do this problem so four goes into two how many times it goes into no times so let's move on to let me switch color so let's move on to the 22 4 goes into 22 how many times let's see 4 times 5 4 times 5 is equal to 20 4 times 6 is equal to 24 so 6 is too much so 4 goes into 22 5 times 5 times 4 is 20 there's gonna be a little bit of a left over and then we subtract 22 minus 20 well that's just 2 and then you bring down this 9 and you saw in the last video exactly what this means right when you wrote this 5 up here notice we were in the hundreds so this is really a 500 but at this video I'm just gonna focus more on the process and you can think more about what it actually means in terms of where I'm writing the numbers but I think the process is gonna be crystal clear hopefully by the end of this video so we brought down the nine four goes into twenty nine how many times see four it goes into at least six times what's four times seven 4 times 7 is 28 so it goes into it at least seven times what's 4 times 8 4 times 8 is 32 so it can't go into an 8 times so it's gonna go to 7 4 goes into 29 7 times 7 times 4 is 28 29-28 to get our remainder for this step in the problem is 1 and now we're gonna bring down this 2 I'm gonna bring it down and you get a 12 4 goes into 12 that's easy 4 times 3 is 12 4 goes into 12 3 times 3 times 4 is 12 12 minus 12 is zero we have no remainder so 4 goes into 2,292 exactly 573 times so this 2,292 divided by 4 we can say is equal to 573 or we could say that this thing right here is equal to 573 let's do a couple more let's do a few more problems let me pick a nice do that red color so say we had 7 7 going into 6000 475 maybe it's called long division because you write it nice and long up here in you know this line I don't know there's multiple reasons where I could be called long division so you say 7 goes into 6 zero times so we need to keep moving forward so 7 so then we go to 64 7 goes into 64 how many times we'll see seven seven times seven is well that's way too small let me think about it a little bit well 7 times 9 is 63 that's pretty close and then 7 times 10 is going to be too big 7 times 10 is 70 so that's too big so 7 goes into 64 or nine times nine times seven is sixty-three sixty-four minus 63 to get our remainder this stage is one bring down the seven bring down the seven seven goes into 17 how many times well 7 times 2 is 14 and then seven times three is twenty-one so three is too big so seven goes into 17 2 times 2 times 7 is 14 17 minus 14 is three and now we bring down the five we bring down the five and 7 goes into 35 that's in our seven multiplication tables 5 times 5 times 7 is 35 five times 5 times 7 is 35 and there you go and so the remainder is zero so all the examples I did so far had no remainders let's do one that maybe might have a remainder and to ensure it has a remainder I'll just make up the problem it's much easier to make problems that have remainders and the ones that don't have remainders so let's say I want to divide three let's say I want to divide 3 into I'm gonna divide it into let's say 1 7 3 5 0 9 2 this will be a nice beastly problem so if we can do this we can handle everything this is one million seven hundred thirty five thousand and ninety two that's what we're dividing 3 into so 3 goes and actually I'm not sure if this will have a remainder and in the future video I'll show you whether whether how to figure out whether something is divisible by 3 actually we can do it right now we just add up all these digits 1 plus 7 is 8 8 plus 3 is 11 11 plus 5 is 16 16 plus 9 is 25 25 plus 2 is 27 so actually this number is divisible by 3 so if you add up all of the digits you get 27 and then you can add up those digits 2 plus 7 is 9 so that is divisible by 9 and that's a trick that only works for 3 so this number actually is divisible by 3 so let me let me change it a little bit so it's not divisible by 3 let me put a let me make this into a let me make this into a one now this number will not be divisible by three I definitely want a number where I'll end up with a remainder just to just so you see what it looks like so let's do this one three go this is into one zero time so we can just move forward you could write a zero here and multiply that out and that just makes it a little bit messy in my head so three so we just move one to the right three goes into 17 how many times well 3 times 5 is equal to 15 and 3 times 6 is equal to 18 and that's too big so 3 goes into 17 or right here 5 times 5 times 3 is 15 and we subtract 17 minus 15 is 2 and now we bring down this 3 set 3 goes into 23 how many times well 3 times 7 is equal to 21 and 3 times 8 is too big that's equal to 24 so 3 goes into 23 seven times 7 times 7 times 3 is 21 and we subtract 23 minus 21 is 2 now we bring down the next number we bring down the 5 I think can appreciate why it's called long division now we bring down this 5 3 goes into 25 how many times well 23 times 8 gets you pretty close and 3 times 9 is too big so it goes into it 8 times 8 times 3 is 24 I'm going to run out of space you subtract you get 125 minus 24 is 1 now we can bring down this 0 you bring down this 0 just like that and you get 3 goes into 10 how many times well that's easy goes into it 3 times 3 times 3 is 9 that's about as close to 10 as we can get 3 times 3 is 9 10 minus 9 I'm gonna have to scroll up and down here a little bit 10 minus 9 is 1 and then we can bring down the next number I'm running out of colors I can bring down that 9 3 goes into 19 how many times well 6 is about as close as we can get that gets to 18 so 3 times 6 so he goes into 19 6 times 6 three let me scroll down six times three is eighteen nineteen minus eighteen we subtracted up here - 19 - eighteen is one and then we're almost done I can revert back to the pink we bring down this one right there and bring down that one 3 goes into 11 how many times well that's three times because three times four is too big it's three three times four is 12 so that's too big so it goes into three times so 3 goes into 11 three times three times three is nine and then we subtract and we get a two and there's nothing left to bring down right and when we look up here there's nothing left to bring down so we're done so we're left with a remainder of 2 after doing this entire problem so the answer 3 goes into 1 million seven hundred thirty five thousand and ninety one it goes into it five hundred and seventy eight thousand three hundred sixty three remainder two and that remained or two is what we got all the way down there so hopefully you now appreciate that you can tackle pretty much any division problem and you also through this exercise can appreciate why it's called long division