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Subtracting a fraction from a whole number

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    - [Instructor] Let's say
    we wanted to figure out
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    what six minus 3/4 is equal to.
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    Pause this video and work
    through this on your own
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    before we work through this together.
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    All right, now there's a couple of ways
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    that we could think about this.
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    The first way is we could
    represent this six wholes
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    as a bunch of fourths.
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    So how many fourths is six wholes?
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    Well, we already know
    that one is equal to 4/4.
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    So six wholes, that's
    gonna be six times as many.
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    So instead of 4/4, you're
    going to have 24/4.
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    So, 24/4 is the same as six.
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    And you could see that
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    because you're going
    to use 4/4 for a whole.
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    And you could do that six times.
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    And now, we can subtract
    the 3/4 from that.
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    And what does that get us?
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    Well, if I have 24 of something
    minus three of something,
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    that's going to be 21 of that something.
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    So, 24/4 minus 3/4 is 21/4.
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    Now, there's another way that
    you could think about this.
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    You could say,
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    well, six is the same
    thing as five plus one.
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    And you might say, why would I do that?
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    Well, if you have one here,
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    you could subtract 3/4 from that.
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    So you could subtract three,
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    lemme do that in a different color.
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    You could subtract the
    3/4 now from the one.
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    And so this is going to
    be equal to five plus,
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    and let's rewrite one over here.
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    Lemme just do it in a different color.
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    I'm having trouble changing colors today.
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    One is how many fourths?
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    Well, we already wrote it over here.
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    It's 4/4.
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    So that's 4/4 minus 3/4.
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    And what is that going to be equal to?
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    Well, that's going to
    be equal to, once again,
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    we have this five over here plus
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    4/4 minus 3/4 is, of course,
    this is going to be one.
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    This over here is going to be 1/4.
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    So you get five plus 1/4
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    is going to be equal to five and 1/4.
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    You might say, hey, is that
    the same thing as 21/4?
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    Well, yes it is because five is what?
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    That's the same thing as 20/4.
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    So it says 20/4 plus 1/4, which is 21/4.
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    Another way you could think about this,
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    if you were to take four,
    it goes into 21 five times
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    with a remainder of one.
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    So there's many different ways
    that you could approach this.
Title:
Subtracting a fraction from a whole number
Description:

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Video Language:
English
Team:
Khan Academy
Duration:
02:34

English subtitles

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