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It always helps me to see a lot
of examples of something so I
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figured it wouldn't hurt to
do more scientific
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notation examples.
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So I'm just going to write a
bunch of numbers and then write
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them in scientific notation.
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And hopefully this'll cover
almost every case you'll ever
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see and then at the end of this
video, we'll actually do some
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computation with them to just
make sure that we can
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do computation with
scientific notation.
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Let me just write down
a bunch of numbers.
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0.00852.
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That's my first number.
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My second number
is 7012000000000.
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I'm just arbitrarily
stopping the zeroes.
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The next number is 0.0000000
I'll just draw a couple more.
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If I keep saying 0, you
might find that annoying.
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500 The next number --
right here, there's a
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decimal right there.
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The next number I'm going
to do is the number 723.
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The next number I'll do -- I'm
having a lot of 7's here.
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Let's do 0.6.
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And then let's just do one more
just for, just to make sure
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we've covered all of our bases.
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Let's say we do 823 and then
let's throw some -- an
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arbitrary number of 0's there.
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So this first one, right here,
what we do if we want to write
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in scientific notation, we want
to figure out the largest
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exponent of 10 that
fits into it.
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So we go to its first
non-zero term, which
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is that right there.
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We count how many positions to
the right of the decimal point
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we have including that term.
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So we have one, two, three.
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So it's going to
be equal to this.
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So it's going to be equal
to 8 -- that's that guy
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right there -- 0.52.
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So everything after that
first term is going to
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be behind the decimal.
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So 0.52 times 10 to the
number of terms we have.
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One, two, three.
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10 to the minus 3.
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Another way to think of it:
this is a little bit more.
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This is like 8 1/2
thousands, right?
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Each of these is thousands.
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We have 8 1/2 of them.
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Let's do this one.
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Let's see how many 0's we have.
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We have 3, 6, 9, 12.
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So we want to do -- again,
we start with our largest
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term that we have.
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Our largest non-zero term.
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In this case, it's going
to be the term all
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the way to the left.
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That's our 7.
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So it's going to be 7.012.
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It's going to be equal to
7.012 times 10 to the what?
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Well it's going to be times 10
to the 1 with this many 0's.
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So how many things?
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We had a 1 here.
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Then we had 1, 2, 3, 4, 5,
6, 7, 8, 9, 10, 11, 12 0's.
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I want to be very clear.
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You're not just
counting the 0's.
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You're counting everything
after this first
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term right there.
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So it would be equivalent
to a 1 followed by 12 0's.
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So it's times 10
to the twelfth.
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Just like that.
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Not too difficult.
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Let's do this one right here.
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So we go behind our
decimal point.
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We find the first
non-zero number.
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That's our 5.
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It's going to be equal to 5.
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There's nothing to the right of
it, so it's 5.00 if we wanted
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to add some precision to it.
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But it's 5 times and then how
many numbers to the right, or
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behind to the right of the
decimal will do we have?
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We have 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, and we
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have to include this one, 14.
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5 times 10 to the
minus 14th power.
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Now this number, it might be a
little overkill to write this
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in scientific notation, but it
never hurts to get
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the practice.
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So what's the largest 10
that goes into this?
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Well, 100 will go into this.
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And you could figure out 100 or
10 squared by saying, "OK, this
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is our largest term." And then
we have two 0's behind it
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because we can say 100
will go into 723.
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So this is going to be equal to
7.23 times, we could say times
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100, but we want to stay in
scientific notation, so I'll
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write times 10 squared.
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Now we have this
character right here.
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What's our first non-zero term?
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It's that one right there, so
it's going to be 6 times and
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then how many terms do we have
to the right of the decimal?
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We have only one.
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So times 10 to the minus 1.
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That makes a lot of sense
because that's essentially
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equal to 6 divided by 10
because 10 to the minus
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1 is 1/10 which is 0.6.
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One more.
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Let me throw some commas
here just to make this a
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little easier to look at.
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So let's take our largest
value right there.
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We have our 8.
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This is going to be 8.23 -- we
don't have to add the other
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stuff because everything else
is a 0 -- times 10 to the --
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we just count how many
terms are after the 8.
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So we have 1, 2, 3, 4,
5, 6, 7, 8, 9, 10.
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8.23 times 10 to the 10.
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I think you get the idea now.
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It's pretty straightforward.
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And more than just being able
to calculate this, which is a
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good skill by itself, I want
you to understand why
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this is the case.
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Hopefully that last
video explained it.
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And if it doesn't, just
multiply this out.
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Literally multiply 8.23
times 10 to the 10 and
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you will get this number.
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Maybe you could try it
with something smaller
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than 10 to the 10.
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Maybe 10 to the fifth.
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And well, you'll get a
different number but
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you'll end up with five
digits after the 8.
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But anyway, let me do a couple
more computation examples.
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Let's say we had the numbers
-- let me just make something
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really small -- 0.0000064.
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Let me make a large number.
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Let's say I have that number
and I want to multiply it.
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I want to multiply it by --
let's say I have a really large
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number -- 3 2 -- I'm just going
to throw a bunch of 0's here.
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I don't know when
I'm going to stop.
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Let's say I stop there.
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So this one, you
can multiply out.
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But it's a little difficult.
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But let's put it into
scientific notation.
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One, it'll be easier to
represent these numbers and
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then hopefully you'll see that
the multiplication actually
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gets simplified as well.
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So this top guy right here,
how can we write him in
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scientific notation?
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It would be 6.4 times
10 to the what?
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1, 2, 3, 4, 5, 6.
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I have to include the 6.
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So times 10 to the minus 6.
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And what can this
one be written as?
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This one is going to be 3.2.
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And then you count how many
digits are after the 3.
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1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11.
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So 3.2 times 10 to the 11th.
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So if we multiply these two
things, this is equivalent to 6
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-- let me do it in a different
color -- 6.4 times 10 to
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the minus 6 times 3.2
times 10 to the 11th.
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Which we saw in the last video
is equivalent to 6.4 times 3.2.
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I'm just changing the order
of our multiplication.
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Times 10 to the minus 6
times 10 to the 11th power.
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And now what will
this be equal to?
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Well, to do this, I don't
want to use a calculator.
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So let's just calculate it.
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So 6.4 times 3.2.
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Let's ignore the
decimals for a second.
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We'll worry about
that at the end.
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So 2 times 4 is 8,
2 times 6 is 12.
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Nowhere to carry the
1, so it's just 128.
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Put a 0 down there.
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3 times 4 is 12, carry the 1.
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3 times 6 is 18.
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You've got a 1
there, so it's 192.
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Right?
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Yeah.
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192.
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You had them up and you
get 8, 4, 1 plus 9 is 10.
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Carry the 1.
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You get 2.
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Now, we just have to
count the numbers behind
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the decimal point.
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We have one number there, we
have another number there.
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We have two numbers behind
the decimal point,
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so you count 1, 2.
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So 6.4 times 3.2 is equal to
20.48 times 10 to the -- we
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have the same base here, so we
can just add the exponents.
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So what's minus 6 plus 11?
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So that's 10 to the
fifth power, right?
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Right.
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Minus 6 and 11.
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10 to the fifth power.
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And so the next question,
you might say, "I'm done.
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I've done the computation."
And you have.
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And this is a valid answer.
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But the next question is is
this in scientific notation?
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And if you wanted to be a real
stickler about it, it's not in
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scientific notation because we
have something here that could
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maybe be simplified
a little bit.
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We could write this --
let me do it this way.
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Let me divide this by 10.
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So any number we can
multiply and divide by 10.
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So we could rewrite
it this way.
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We could write 1/10 on this
side and then we can multiply
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times 10 on that side, right?
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That shouldn't
change the number.
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You divide by 10 and
multiply it by 10.
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That's just like multiplying
by 1 or dividing by 1.
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So if you divide this side
by 10, you get 2.048.
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You multiply that side by
10 and you get times 10 to
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the -- times 10 is just
times 10 to the first.
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You can just add the exponents.
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Times 10 to the sixth.
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And now, if you're a stickler
about it, this is good
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scientific notation
right there.
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Now, I've done a lot
of multiplication.
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Let's do some division.
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Let's divide this
guy by that guy.
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So if we have 3.2 times 10 to
the eleventh power divided by
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6.4 times 10 to the minus
six, what is this equal to?
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Well, this is equal
to 3.2 over 6.4.
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We can just separate them out
because it's associative.
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So, it's this times 10
to the 11th over 10 to
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the minus six, right?
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If you multiply these
two things, you'll
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get that right there.
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So 3.2 over 6.4.
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This is just equal
to 0.5, right?
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32 is half of 64 or 3.2
is half of 6.4, so this
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is 0.5 right there.
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And what is this?
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This is 10 to the 11th
over 10 to the minus 6.
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So when you have something
in the denominator, you
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could write it this way.
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This is equivalent to 10 to the
11th over 10 to the minus 6.
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It's equal to 10 to the
11th times 10 to the
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minus 6 to the minus 1.
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Or this is equal to 10 to the
11th times 10 to the sixth.
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And what did I do just there?
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This is 1 over 10
to the minus 6.
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So 1 over something is just
that something to the
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negative 1 power.
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And then I multiplied
the exponents.
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You can think of it that way
and so this would be equal
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to 10 to the 17th power.
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Or another way to think about
it is if you have 1 -- you have
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the same bases, 10 in this
case, and you're dividing them,
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you just take the 1 the
numerator and you subtract the
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exponent in the denominator.
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So it's 11 minus minus
6, which is 11 plus 6,
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which is equal to 17.
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So this division problem
ended up being equal to
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0.5 times 10 to the 17th.
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Which is the correct answer,
but if you wanted to be a
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stickler and put it into
scientific notation, we want
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something maybe greater
than 1 right here.
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So the way we can do
that, let's multiply
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it by 10 on this side.
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And divide by 10 on this
side or multiply by 1/10.
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Remember, we're not changing
the number if you multiply
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by 10 and divide by 10.
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We're just doing it to
different parts of the product.
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So this side is going to become
5 -- I'll do it in pink -- 10
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times 0.5 is 5, times 10 to
the 17th divided by 10.
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That's the same thing as
10 to the 17th times 10
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to the minus 1, right?
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That's 10 to the minus 1.
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So it's equal to 10
to the 16th power.
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Which is the answer when
you divide these two
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guys right there.
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So hopefully these examples
have filled in all of the
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gaps or the uncertain
scenarios dealing with
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scientific notation.
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If I haven't covered something,
feel free to write a comment on
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this video or pop me an e-mail.