WEBVTT

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We're told that Linde isn't sure
how to subtract 853...

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We are told Linde isn't sure

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how to subtract 853 minus 283.

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Help Linde by choosing an expression

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that is the same as 853 minus 283.

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So, pause this video and see
if you can answer it on your own

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before we work through it together.

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Alright, now that we look
at all the choices,

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they all start with 853.

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Now, this first choice
they subtract out 200

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That makes sense
because we have 2 hundreds

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right over there.

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Then they subtract out 50

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and then they subtract out 3,

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So, the 200 and the 3 make sense.

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You can view 853 minus 283

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as 853 minus 200,

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minus 80, 8 tens right here,

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minus 3.

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But that's not what they wrote over here.

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Instead of putting 80 here,
they put a 50.

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So we can rule that out.

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Here we have 853 minus 20

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minus 800 minus 3.

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Well, this is a little bit strange

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because we don't have 2 tens,
we have 2 hundreds

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and we don't have 8 hundreds,
we have 8 tens,

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so this is also incorrect.

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Now, it's probably going to be this one,

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but let's just make sure
we feel comfortable with this.

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So, this one has 853 minus 200,

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minus 53.

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minus 30.

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Does that make sense?

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Well, let's think about it.

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What they're doing,

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is they're subtracting out first the 200,

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so that this part right over here,
so that makes sense.

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They're subtracting out first that.

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And then they're subtracting out 53

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and then subtracting out 30.

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Well, that is the same thing

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as subtracting out 83,

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because subtracting out 83

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is the same thing
as subtracting out 53 and

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and then subtracting 30.

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53 plus 30 is 83.

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Now, you might be wondering

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why would they even do it this way?

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What is easier to do in your head?

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853 minus 200 is 653.

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You take away 53 from that,

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so you take away 53 from that,

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and you're going to be left with 600.

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And then 600 minus 30

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— you might recognize that,

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you could do 60 tens minus 3 tens —

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it's going to be 57 tens,

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or you might be able
to do it in your head

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600 minus 30 is 570.

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So, that's why they broke out,

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they broke up the 83.

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Instead of just breaking it up
into 80 and 3,

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they broke it up into 53 and 30
to match this 53 over here.

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It's easier to work out the result.

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Let's do another example.

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So, here we're asked to fill in the blank.

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They say, 143 minus 79
is the same as "blank" minus 80.

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So, pause this video
and see if you can figure this out.

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So, the key here is to realize

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is, when you have a difference here,

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as long as you add or subtract
the same amount

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to both of these,

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the difference will be the same.

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So, it looks like they tried
to turn 79 into,

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it looks like they turned
the 79 into an 80,

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by adding 1

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and so if we want the difference
to be the same,

NOTE Paragraph

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we would add 1 to the 143 as well,

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So, 143 plus 1 is 144.

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If we add one to both of these numbers,

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the difference would be the same.

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And we're done.

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So it's 144 minus 80.