Transcript Converting Fractions to Decimals PPT

I juggled
Granny’s china
teacups…..
once!
© Mike’s Math Mall
My bad!
Hi!
My name’s
Sparky!
Not that kind of introduction, big fella!
Fractions, decimals, and percents
are different ways of
representing the same number.
𝟏
𝟐
Fraction
= 0.5 = 50%
Decimal
Percent
These numbers look different, but
they all have the exact same value.
Because we use fractions, decimals,
and percents in everyday life, it’s
helpful if we can juggle or change
between each form…
…making these numbers
easier to
I understand
that ¼ pound of
understand.
cheesy bacon burger
is good!
Hopefully, you just had
an off day!
I don’t
understand how
I got a 25% on
my last math
test.
When do we use
Fractions?
Cooking/Recipes
𝟐
cups flour
𝟑
Measuring Length
𝟏
𝟓 inches
𝟖
Telling time
𝟏
after four
𝟒
(a quarter after four)
Reading Music
𝟏
note
𝟐
Can you think of other ways we use fractions?
When do we use
Decimals?
Prices
Sports
0.375 – baseball
batting averages
Gas Amounts
18.8959 gallons
Pi
𝜋
3.141592…
Where else do we see decimals?
When do we use
Grades
25%
Percents?
Thanks
for reminding
me!
Tipping Rates
15% to 20%
Retail Sales
60% off!
Statistics
100% of students choose
shorter school days!
Where else do we find percentages?
A fraction is formed by two numbers;
a top number, the numerator, over a
bottom number, the denominator.
→
𝐧𝐮𝐦𝐞𝐫𝐚𝐭𝐨𝐫
𝐝𝐞𝐧𝐨𝐦𝐢𝐧𝐚𝐭𝐨𝐫 →
3
4
or
𝒑𝒂𝒓𝒕
𝒘𝒉𝒐𝒍𝒆
Proper fractions, like this one,
represent numbers less than 1.
Decimals are related to fractions
because they also represent
numbers less than 1.
Does anyone know how to turn a
fraction into a decimal?
how
If you said by dividing does But
that give you
a decimal?
the numerator by the
denominator, you’re right!
Check this out!
𝟑
𝟑
turnLet’s
intouse
a decimal,
weexample.
divide the
as
an
𝟒
𝟒
To
numerator, 3, by the denominator, 4.
0 . 75
4 3.0 0
-2 8
20
-20
0
𝟑
So
𝟒
=
0.75
Hint: you can think of
a fraction bar like a
division (÷) symbol.
Can someone guess what the decimal
form of
𝟑
3
𝟒
would be?
If you said 3.75, you’re right!
Notice how the whole
I think
I get it, but can
number stays the
we do one more
to be sure?
same in both forms.
Absolutely!
𝟐
Let’s change 5 into a decimal!
𝟑
Remember! The whole number will stay the
same, so we just need to divide 2 by 3.
0. 66
3 2.0 00
I’m
still iffy!
-1 8
20
-18
20
Let’s practice!
At this point, you can
see the division problem
will never end, and the
6 will keep repeating.
𝟐
So 5
𝟑
= 5.6
Change the following fractions into decimals.
A percentage represents
an amount out of 100.
We use the (%) symbol instead of writing
fractions with a denominator of 100.
My bad!
It’s time
So, for example,
we find another
example!
instead of saying Sparky
got 25 out of 100 on his last
math test, we say Sparky got a 25%.
Because a percentage represents
an amount out of 100, to turn a
decimal into a percent, all we do is
multiply the decimal by 100.
Let’s change 0.62 to a percent!
100
× 0.62
200
+ 600
62.00
= 62
Don’t forget the
percent sign!
62%
Someone
told me that when
you multiply by 100, it’s
just like moving the
decimal point 2 places
to the right!
Got it!
Moving
the decimal
seems waaaaay
easier to me!
That someone
was correct!
It is! Just don’t forget to add
the percent sign after you
move the decimal!
So, let’s use Sparky’s method to easily
change some decimals into percents.
Example 1:
0.45 → 45.0 = 45%
Example 2:
0.70 → 70.0 = 70%
Before we can move the
decimal 2 places to the right,
we have to add a zero.
Example 3:
1.25 → 125.0 = 125%
Example 4:
2.00 → 200.0 = 200%
An “understood” decimal
comes after the 2.
I’m
pretty sure I
have this!
Add two zeros so we
can move the decimal!
We better practice just to be sure!
Change the following decimals into percentages.
Me thinks
me gettin’
dizzy!
This won’t be bad. Trust me!
If we move the decimal 2 places to the
right to change a decimal to a percent,
what do you suppose we do to change a
percent back to a decimal?
Move the
decimal 2 places
to the left?
What
can I say? It
runs in the
family!
Pure genius!
Just check this out, Professor Sparkington!
Example 1:
85.% → .85 = 0.85
Locate the “understood”
decimal after the 5 and
remove the percent sign.
Then, move the decimal
2 places to the left.
Example 2:
30.% → .30 = 0.3
Example 3:
115.% = 1.15
Your turn!
Change the following percents into decimals.
Head…
about…to…
explode!
Stay with me Sparticus!
Before we start changing decimals into
fractions, we need a good understanding
of how to properly say decimals.
Believe it or not, when you
properly say a decimal,
you are automatically
say
I’llSome
believe
crazy!I Others
it when
see it…
creating the fraction.
cute!
orsay
hear
it!
Well, at least the crazy face is gone!
Can you name the following
decimal place values?
(Sample number)
Now let’s look
at how to
properly “say”
decimals.
Practice saying the following decimals:
As you say each decimal, picture the fraction
you’re saying to yourself:
What work still needs to be done with
all of these fractions?
If you said “simplify,” you’re right!
Simplify.
I get it!
But I better
do some more
practice.
I like your
attitude!
Change the following decimals into fractions.
Don’t forget to simplify!
So how’d you do on the
practice problems, Sparky?
I believe
I have this stuff
covered, sir!
Who wants
to see a belly
roll?
Well, maybe it’s time we work on
getting some other things covered!
© Mike’s Math Mall