WEBVTT

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Use the commutative law of
addition-- let me underline

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that-- the commutative law
of addition to write the

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expression 5 plus 8 plus 5
in a different way and

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then find the sum.

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Now, this commutative law of
addition sounds like a very

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fancy thing, but all it means
is if you're just adding a

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bunch of numbers, it doesn't
matter what order you add the

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numbers in.

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So we could add it as
5 plus 8 plus 5.

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We could order it as
5 plus 5 plus 8.

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We could order it
8 plus 5 plus 5.

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These are all going to add up
to the same things, and it

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makes sense.

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If I have 5 of something and
then I add 8 more and then I

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add 5 more, I'm going to get
the same thing as if I had

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took 5 of something, then added
the 5, then added the 8.

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You could try all
of these out.

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You'll get the same thing.

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Now, they say in a different
way, and then find the sum.

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The easiest one to find the sum
of-- actually, let's do

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all of them.

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But the easiest one, just
because a lot of people

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immediately know that 5 plus 5
is 10, is to maybe start with

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the 5 plus 5.

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So if you have 5 plus
5, that's 10, plus

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8 is equal to 18.

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Now, let's verify that these two
are the same exact thing.

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Up here, 5 plus 8 is 13.

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13 plus 5 is also 18.

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That is also 18.

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If we go down here,
8 plus 5 is 13.

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13 plus 5 is also equal to 18.

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So no matter how you do it and
no matter what order you do it

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in-- and that's the commutative
law of addition.

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It sounds very fancy, but it
just means that order doesn't

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matter if you're adding
a bunch of things.