Transcript guess t shirt

So what’s
the point?
Get it?
PowerPoint
© Mike’s Math Mall
We round numbers to make them easier
to use and understand while keeping
them close to their actual value.
Hey!
That
sounds
But
I got
unit…
aBad
like
a lot
54%
on
Fractions!
estimating.
that
baby!
Bad day?
Can
Umm…
you
give
About
methat
an
example?
test…
Right!Your
Yourlast
teacher
Sure!
math
That’s
right!
We
round
rounded
the
grade
to
test
grade
was
actually
Ouch!
to
help
us
estimate.
makeait53.846%.
easier
to use
and understand.
Here are some
real-world
examples
Sales
tax – always
rounded
where to
numbers
are rounded:
the nearest
penny.
Time/Distance/Amount – rounded
for easier understanding.
Mental math – rounding numbers
helps us do math in our heads.
(Sample number)
tenths
hundredths
thousandths
hundreds
tens
ones
hundred thousands
ten thousands
thousands
millions
Can you name all of the
place value positions
below?
5, 267, 418 . 391
That’s a
lot of places
for one kid to
remember!
Head…
about…to
explode!
Sparky! You can do this!
Confidence is
the key!
I’m guessing
in order to round
numbers, you really
need to understand
place value.
I think I
do, and my brain
pain is going
away!
You guessed correctly,
so hopefully you have all
your place values down!
That’s my
champ!
Let’s round some whole numbers!
Example 1:
Round the following number to the nearest hundred.
5,368
Step 1: Underline the hundred’s place.
Step 2: Look at the number to the right of
the underlined digit.
Example 1 continued:
Round the following number to the nearest hundred.
5,368 = 5,400
Step 3: If the number on the right is 4 or less, leave the
underlined number alone, and turn all digits on
the right side of the underlined number into zeros.
or
Step 3: If the number on the right is 5 or more, add one
to the underlined number, and then turn the rest
of the digits on the right into zeros.
Example 2:
Round the following number to the nearest ten thousand.
683,261 = 68 0,000
Step 1: Underline the ten thousand’s place.
Step 2: Look at the number to the right of the 8.
Step 3: Leave 8 alone because 3 is “four or less.”
Step 4: All numbers to right of the underlined
number turn into zeros.
Example 3:
Round the following number to the nearest ten.
496 = 500
Step 1: Underline.
Step 2: Look to the right of 9.
Step 3: Round the 9 up to 10 and carry the 1 over
to the 4, making it a 5.
Step 4: All numbers to right of the underlined
number turn to zero.
Let’s practice!
Round the following numbers to the place indicated.
1) thousands; 14,023
2) tens; 21,485
14,000
21,490
3) millions; 63,502,019
4) hundreds; 757,839
64,000,000
5) hundred thousands; 181,215
200,000
7) tens; $641.43
$640.00
757,800
6) ten thousands; 397,216
400,000
8) hundreds; 7,985
8,000
I think
I get rounding, but
we still need to round
decimals. Is there
any difference?
Sounds
reasonably
painless!
We follow the exact same steps,
but at the end, instead of turning
numbers into zeros, we just
remove them!
Check this
out!
Example 1:
Round the following decimal to the nearest hundredth.
1.252 = 1.25 2
Step 1: Underline.
Step 2: Look to the right of 5.
Step 3: The 5 stays the same.
Step 4: Cut off all numbers to the right of the
underlined number.
Example 2:
Round the following decimal to the nearest tenth.
9.473 = 9.5 73
Round the 4 to a 5, and remove all digits
to the right of the underline number.
Example 3:
Round the following money amount to the nearest penny.
$3.985 = $3.99
Round the 8 up to a 9.
Remove the 5.
Don’t forget the dollar sign!
Let’s practice!
Round the following decimals to each underlined place.
1. 8.5
2. 0.624
9
0.62
3. 3.781
4. 1.7316
3.8
5. 9.865
9.87
7. $7.4951
$7.50
1.732
6. 0.952
1 or 1.0
8. $862.99
$860.00
Round the following numbers to the indicated place.
1)
thousandths; 0.0644
2)
0.064
3)
hundredths;
4.888
thousandths;
4)
tenths;
114.34
114.3
2.7515
2.752
7)
0.798
0.8
4.89
5)
tenths;
nearest penny;
6)
hundredths;
4.996
5 or 5.00
$55.386
$55.39
8) nearest dime; $65.46
$65.50
So, how’d you do on
the practice problems,
Sparky?
I did great,
sir, and I’m going to
try rounding everything
“up” the next time
I eat!
But then no
one will be able to
see my well-rounded
belly!
© Mike’s Math Mall
Well, the next time you go
shopping, how about rounding
“up” to the next shirt size?
My job here
is done!