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