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Current time:0:00Total duration:4:19

Video transcript

the new headquarters of Khan Academy is at 3:1 for math Avenue it has 200 windows and has seven stories the parking lot can fit 90 cars the building itself is 63 feet tall how tall is each story so I encourage you to pause this video and try this on your own so let's try to answer it they're asking us how tall is each story so what information do we need well we definitely don't need the address we don't care how many windows it has now the number of stories seems interesting especially because they tell us the total number of feet or the total height of the building for example they tell us that the building is 63 feet tall so this height right over here the building's height is 63 feet tall and they tell us that it has seven storeys seven stories so one two three four five six and seven so it has seven stories so if we divide 63 by seven we should figure out how tall each story is so let's do that we're going to divide 63 feet divided by divided by seven stories and this is going to tell us how tall each story is so that's going to be equal to question mark now 63 divided by seven being equal to question mark this is another way of saying that seven times question mark is going to be equal to 63 let me write that down so this is another way of saying that 63 is equal to is equal to seven seven times times question mark times question mark so if we can figure out what do we have to multiply 7 by to get to 63 then we know what 63 divided by 7 is and to do that I'm just going to skip count by seven so let's start with seven so seven times one is seven seven so let me just write this so 7 times 1 is 7 7 times 2 is 14 seven times three is twenty-one seven times four is twenty-eight notice I'm just adding by seven each time seven times five is thirty-five seven times 6 is 42 seven times seven is forty-nine seven times eight is fifty-six just adding 7 7 times 9 is 63 so we see 7 times 9 is 63 so the question mark must be equal to 9 question mark must be equal to 9 so we can write that 63 divided by 7 63 63 divided by 7 let me do those same colors that I just used 63 divided by 7 is equal to 9 divided by 7 is equal to 9 and let's let's think about that we're saying that if we three feet and divide it into seven equal stories that each story is going to be nine feet on average does that make sense so does it make sense that each of these each of these stories are going to be 9 feet well we have 7 of them so it should be at just the first story should be nine feet by the time we get to the second story we should be at 18 feet I'm adding by 9 now third story the top of the third story should be 27 feet top of the fourth story is going to be 36 feet top of the fifth story is going to be 45 feet top of the sixth story is going to be 54 feet and then the top of the seventh story which is also the top of the building is going to be 63 feet so if each floor is 9 feet high you just have to keep adding 9 every time you add a floor and you see if you do that if you have seven floors you're going to get 263 feet so it completely makes sense eat each story is 9 feet tall