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Negative number word problem: temperatures

Use a number line to solve a word problem that includes a negative number. Created by Sal Khan.

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  • female robot grace style avatar for user npsridharan28
    At Sal mentioned the absolute value. What is the absolute value?
    (15 votes)
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    • starky ultimate style avatar for user Patrick
      The absolute value is the distance a certain number is from 0. For example, the absolute value of 5 is 5, because it is 5 units away from zero. The | | symbols represent absolute value, so if you have something like |-9|, you find the absolute value of -9, which is nine.
      (30 votes)
  • duskpin tree style avatar for user aaliyah.hubbard
    math is.... interesting..
    (9 votes)
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  • starky tree style avatar for user Ellie S.
    Hey, hey
    Bye bye bye, bye bye
    Bye bye

    I'm doing this tonight
    You're probably gonna start a fight
    I know this can't be right
    Hey baby come on
    I loved you endlessly
    When you weren't there for me
    So now it's time to leave and make it alone
    I know that I can't take no more
    It ain't no lie
    I want to see you out that door
    Baby bye bye bye
    Don't want to be a fool for you
    Just another player in your game for two
    You may hate me but it ain't no lie
    Baby bye bye bye
    Bye bye
    Don't really want to make it tough
    I just want to tell you that I've had enough
    It might sound crazy but it ain't no lie
    Baby bye bye bye
    You just hit me with the truth
    Now girl you're more than welcome to
    So give me one good reason
    Baby come on
    I've lived for you and me
    And now I really come to see
    That life would be much better once you're gone
    I know that I can't take no more
    It ain't no lie
    I want to see you out that door
    Baby bye bye bye
    Don't want to be a fool for you
    Just another player in your game for two
    You may hate me but it ain't no lie
    Baby bye bye bye
    Bye bye
    Don't really want to make it tough
    I just want to tell you that I've had enough
    Might sound crazy but it ain't no lie
    Baby bye bye bye
    I'm giving up I know for sure
    I don't' want to be the reason for your love no more
    Bye bye
    I'm checking out, I'm signing off
    I don't want to be the loser, and I've had enough
    I don't want to be your fool in this game for two
    So I'm leaving you behind
    (Bye bye bye)
    I don't want to make it tough
    (Make it tough)
    But I've had enough
    And it ain't no lie
    Don't want to be a fool for you
    Just another player in your game for two
    I don't want to be your fool
    But it ain't no lie
    Baby bye bye bye
    Bye bye
    Don't really want to make it tough
    I just want to tell you that I've had enough
    It might sound crazy but it ain't no lie
    Bye bye
    (6 votes)
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  • blobby green style avatar for user ROSA288
    why do we need the vertical number line thought?
    (5 votes)
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  • blobby green style avatar for user 39619
    Save me someone
    (5 votes)
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  • old spice man blue style avatar for user TTG_fireball
    im... slowley.... dying

    mathhhhhhhhhhhhhhhhhhhh

    why Y R U SO terible

    i cant stand any moooooore

    yyyyyyyy does it have to be bad

    yyyyyyyy just ask my dad
    (4 votes)
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  • leaf green style avatar for user starknv
    It's been a long time since anyone has asked a question
    (3 votes)
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  • duskpin seedling style avatar for user lego brickster
    this is a pain even more of a pain as taxes im gonna hav to do
    (3 votes)
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  • piceratops seedling style avatar for user NutterButter34
    NutterButter
    (3 votes)
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  • male robot hal style avatar for user sky
    hello im here to help ask me for anything from this video here
    (2 votes)
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Video transcript

One of the coldest temperatures ever recorded outside was negative 128 degrees Fahrenheit in Antarctica. One of the warmest temperatures ever recorded outside was 134 degrees Fahrenheit in Death Valley, California. How many degrees difference are there between the coldest and warmest recorded outside temperatures? So let's think about this a little bit. Now, what I'll do is I'll plot them on a number line. But I'm going to plot it on a vertical number line that has a resemblance to a thermometer, since we're talking about temperature. So I'm going to make my number line vertical right over here. So there's my little vertical number line. And this right over here is 0 degrees Fahrenheit, which really is of no significance. If it was Celsius, we'd be talking about the freezing point. But for Fahrenheit, that happens at 32 degrees. But let's say this is 0 degrees Fahrenheit. And let's plot these two points. So one of the coldest ever recorded temperatures was negative 128 degrees Fahrenheit. So let's say that's right over here. This is negative 128 degrees Fahrenheit. And one of the warmest temperatures ever recorded was 134 degrees. This is a positive 134. So it's about that far and a little bit further. So it's a positive 134 degrees Fahrenheit. So when they're asking us how many degrees difference are there between the coldest and the warmest, they're essentially saying, well, what is this distance between the coldest and the warmest right over here? What is this distance? And there's a couple of ways you could think about it. You could say, hey, if I started at the coldest temperature and I wanted to go all the way up to the warmest, how much would I have to add? Or you could say, well, what's the difference between the coldest and the warmest? So you could take the larger number. So it's, say, 134. And from that, you could subtract the smaller number, which is negative 128. So this essentially saying what's the difference between these two numbers? It's going to be positive, because we're subtracting the smaller one from the larger one. This is going to give you the exact same thing as this. Now, there's several ways to think about it. One is we know that if you subtract a negative number, that's the same thing as adding the positive of that number, or adding the absolute value. So this is the same thing. This is going to be equal to 134 plus positive 128 degrees. And what's the intuition behind that? Why does this happen? Well, look at this right over here. We're trying to figure out this distance. This distance is 134 minus negative 128. And if you look at that, it's going to be the absolute value of 134. It's going to be this distance right over here, which is just 134-- which is just that right over there-- plus this distance right over here. Now, what is this distance? Well, it's the absolute value of negative 128. It's just 128. So it's going to be that distance, 134, plus 128. And that's why it made sense. This way, you're thinking of what's the difference between a larger number and a smaller number. But since it's a smaller number and you're subtracting a negative, it's the same thing as adding a positive. And hopefully this gives you a little bit of that intuition. But needless to say, we can now figure out what's going to be. And this is going to be equal to-- let me figure this out separately over here. So if I were to add 134 plus 128, I get 4 plus 8 is 12, 1 plus 3 plus 2 is 6. It's 262. This right over here is equal to 262. How many degrees difference are there between the coldest and warmest recorded outside temperature? 262 degrees Fahrenheit difference.