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NAME
DATE
PERIOD
Study Guide and lnteruention
Percents and Decimals
To write a percent as a decimal, divide the percent by 10Q and remove the percent symbol. To write a
decimal as a percent, multiply the decimal by 100 and add the percent symbol.
\Mrite
42.5Vo:
#
42.5Vo
as a decimal.
Write the percent as a fraction.
_ 42.5 x l0
Multiply by 10 to remove the decimal in the numerator.
_
Simplify.
100 x 10
425
1,000
-
0.425
Write the fraction as a decimal.
lVrite 0.625 as a percent.
0.625
:
O62.5
:62.5Vo
Multiply by 100.
Add the % symbol.
Write each percent as a decimal.
L.
67o
2.28Vo
3.
SLVo
4.847o
5.
35.5Vo
6.
t2.5Vo
7.
l4.2Vo
8.
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IVrite each decimal as a percent.
9.0.47
10. 0.03
11. 0.075
t2.0.9L4
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oa
Chapter 5
39
Glencoe MAC 2
DATE
NAME
PERIOD
Study Guide and lnteruention
Least Common Multiple
A multiple of a number is the product of that number and any whole number. The least nonzero
multiple of two or more. numbers is the least common multiple (LCM) of the numbers.
Find the LCM of L5 and 20 by listing multiples.
List the multiples.
multiples of 15: 15, 30, 45,60,75,90, 105, 120, ...
multiples of 2O:20,40,60, 80, 100, 120, 140, ...
Notice that 60,
1,2O,
..., are common multiples. So, the LCM of 15 and 20 is 60.
Find the LCM of 8 and 12 using prime factors.
Write the prime factorization.
8:2X2X2:23
L2:2x2x3:22x8
The prime factors of 8 and 12 are 2 and 3.
Multiply the greatest power of both 2 and 3.
The LCM of 8 and L2is 23 x 3, or 24.
Find the LCM of each set of numbers.
L. 4,6
2.6,9
3. 5,9
4. 9,10
5. L2, L5
6. L5,21
7.4,L5
8. 8,20
9. 8,
L6
LO. 6,14
L2,20
L2.9,L2
13. L4,2L
14.6,L5
15. 4,6,8
16. 3,5,6
I-1r.
Chapter 5
Glencoe MAC 2
PERIOD
DATE
Study Guide and Intervention
Comparing and Ordering Ratipnal Numbers
To compare fractions, rewrite them so they have the same denominator. The least
common
denominator (LCD) of two fractions is the LCM of their denominators.
Another way to compare fractions is to express them as decimals. Then compare the decimals.
lVhich ftaction is greater,
1""
L{
Method 2 Write each fraction as a
Method L Rename using the LCD.
decimal. Then compare decimals.
3
_ 3x5 _
15
f;: o.ts
4 4x5 20
4 _ 4x4 _ L6
5 5x4 20
f:o.t
Because the denominators are the same,
compare numerators.
Since
#,
#,tnen
Since 0.8
>
0.75, then
Lr,
I
f > f.
Find the LCD of each pair of fractions.
1
.11
-' z'B
n37
,.+,1
"' 4'lo
.9
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=*
o
Eo
F
Replace each O with
(, ), or = to make a true sentence.
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Chapter 5
41
Glencoe MAC 2
:
E
DATE
PERIOD
Study Guide and lntervention
Estimating with Fractions
Use rounding to estimate with fraetions.
Estimating:
to
the nearest whole number.
For mixed numbers, round
+[+s{
+|
'-+
+ sf, is
Estirnate
zlx+f,---> Bx4:\2
4+4:,
aboutl.
For fractions, round to
0,
f,
or
t.
+-t +
+-tis
't-+:+
aoout|.
,* 4.
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The product is about 12.
Estimate +
-
g.
$ is about 1.
3.rs aDout
, ,1
U
63.11---> I _-:
7522
-
7.
The difference is about
|.
o
oo
(E'
o
o
Estimate.
.
@
r.af+sf
z.
r
o
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z$xsl
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Chapter 6
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Glencoe MAC 2