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Current time:0:00Total duration:5:09
CCSS.Math: ,

Video transcript

let's divide 9815 by 65 or figure out how many times the 65 go into 9815 and I encourage you to pause this video and try this on your own so let me just rewrite this as 9815 divided by 65 divided by 65 and we write it this way because it's easier to manipulate the numbers kind of doing the standard process here and as we'll see whenever we divide by a number that has more than one digit there's a little bit of an art to it and hopefully you'll get an appreciation for that art over the course of this video so first we can think about well how many times is 65 go into nine well does it go into nine at all so we can move one digit to the right how many times does it go into ninety eight without going over it well 65 times one is 65 so that doesn't go over it and 65 times two well that would be 130 so that would go over 198 so it only goes one time it only goes one time we multiply 1 times 65 which is 65 and then we could subtract to see how much we have left over so 8 minus 5 is 3 and 9 minus 6 is 3 and now we can bring down we can bring down the next digit this one here and now this is where the art is going to come into play because we need to figure out how many times is 65 go into 331 without going over it and it you might just try to look at these numbers try to approximate them a little bit you might say well maybe 65 well let me round this thing up maybe this is close to 70 and let's see this is close to this is close to 300 so maybe we say well 70 would go into 300 so maybe we think about how many times does 70 go in to 300 and we say without going over it it doesn't go exactly into 300 well well you could say well how many times does 7 go into 30 well we know 7 goes into 30 4 times 4 times 7 is 28 so maybe try a 4 right over here because then this will be 284 times 70 is 280 you're still going to have a little bit left over but what you have left over going to be less than 70 it's going to be 20 so you say well if this is roughly 70 and if this is roughly 300 then maybe it's going to be the same thing so let's try that out let's see if it goes four times so four times five is 20 carry the 2 4 times 6 is 24 plus 2 is 26 and now let's see how much we had left over so when we subtract when you subtract we are left with this in a new color 1 minus 0 is 1 we have a 3 here and a 6 here so we have to do a little regrouping let's take 100 from the hundreds place becomes 200 give those 10 tens that hundred to the tens place so now we have 13 tens 13 minus 6 is 7 and then 2 minus 2 is 1 so did this work out well no our remainder after we said it went in four times we actually had 71 left over 71 this right over here is larger than 65 you don't want a situation where what you have left over is larger than what you were trying to divide into the number you could have gone into it one more time and and because you had so much left over so this 4 was actually too low we should have probably approximated this is 60 and 60 goes into 300 if we were to estimate we'd say well that might be closer to 5 times so this is where the art of this comes into play so it was very reasonable to do what I just did but it just turned out to not be the right way to think about it I could just say oh well 4 wasn't enough I had too much left over let me try 5 now 5 times 5 is 25 carry the 2 5 times 6 is 30 plus 2 is 32 there you go we got much closer 331 without going over now we can now we can subtract and once again we could do a little regrouping take 10 from the tens place this becomes 2 tens this becomes an 11 11 minus 5 is 6 2 minus 2 is 0 3 minus 3 is 0 so we only have 6 left over which is obviously less than 65 so we're all good and if we if we put a 6 here and we would have gone over 3 31 and so that wouldn't have been cool either but anyway let's bring down the next digit let's bring down the five so how many times is sixty five go into sixty-five well it goes one time one times 65 and okay ignore this is from a previous step one times 65 is 65 and then you subtract and we have no remainder no remainder so we see that sixty five goes into 9815 exactly exactly 150 let me describe that in that same blue color one hundred and I don't want to do all these arbitrary colors 151 times 151 times