Transcript Math Review

Math Review
Answer Key
1. 10
- 7
2
5
3
4
44
2. 3x - 7 = 53 1. 2 13/203. Simplify 32
2. x=20
4. Estimate3. 15.42 + 6.59 to the
nearest
4. 5.4 + 6.6 tenth.
= 12.0
3/8
5. Which of the following statement is true
a. about
Thesethis
students spend more
5. c
graph?
time at school than doing
anything else.
b. These students spend equal
amounts of time on homework
and watching t.v.
c. These students spend equal
amounts of time on homework
and doing chores.
d. These students spend less
time playing outside than doing
Estimation
Objective: I can make estimates using whole
numbers, decimals, and fractions.
Essential Questions
1. What is estimation? How should you use it to
determine the reasonableness of your answer?
2. What is estimation? Why should you use it to
determine the reasonableness of your answer?
3. What is estimation? When do I use it?
4. What is rounding? Why is it important to
estimation?
Adding & Subtracting
Estimation
You can estimate an answer before
you calculate, to make sure your
answer is reasonable.
The symbol ≈ means “is
approximately equal to.”
Check It Out...
Estimating Decimals
1.Find the place value you want (the
"rounding digit") and look at the digit just to
the right of it.
2. If that digit is less than 5, do not change
the rounding digit but drop digits to the right of
the decimal.
3. If that digit is greater than or equal to five,
add one to the rounding digit and drop digits
to the right of the decimal.
Let’s Try It!
Estimate the following to the given
place value:
74.29 to the nearest tenth 74.3
50.009 to the nearest hundredth50.01
69.45898 to the nearest
thousandth
69.459
203.98
203.978 to the nearest hundredth
Now Try These!
Estimate to the nearest hundredths
place...then solve.
84.034 - 32.982
84.03 - 32.98 = 51. 05
345.0285 + 272.9762
345.03 + 272.98 =72. 05
581.236 - 87.2346
581.24 - 87.23 =494.01
Estimating with
Fractions
Sometimes it is better to round a
fraction to the nearest half in order to
estimate an addition or subtraction
problem…
For Example
3
5
0
It is closer to ½
1
5
2
5
½
3
5
1
Draw a number line
Divide the line up into equal portions
of your denominator’s value
Decide whether it is closer to a whole
or a half
Let’s Try a Couple...
6
7
0
It is closer to 1
1
7
2
7
3
7
½
4
7
5
7
6
7
1
Draw a number line
Divide the line up into equal portions
of your denominator’s value
Decide whether it is closer to a
whole or a half
Estimating Mixed
Numbers
3
Is 5 8 closer to 5, 5½,
or 6?
Draw a number line
Divide the line up into equal portions of
your denominator’s value
Decide whether it is closer to a whole or
a half
5 5 1 5 2 5 3 5½
8
8
8
6
Round these mixed
numbers to the nearest
half…
4
2
2½
3
12
12½
13
8
5 11
5
5½
6
9
6 13
6
6½
7
29
12
5
9
Round Each Fraction
to Add and Subtract
Remem
1
76
+
3
17 +
2
43
7 + 1½ + 5 = 13½
4
95
-
2
69
-
10 - 6 - 3 = 1
5
28
ber...
Estimat
e
first!
Now Let’s Estimate!
Jack has some 24
pieces of licorice rope.
He gives 2 and 3/4
pieces to Jill, 6 and 5/9 to
Jim, and 9 and 9/11 to
June. How much does he
have left for himself?
3 +6½ +10 = 19½
24 - 19½ = 4½
Remem
ber...
Estimat
e
first!
Now You Try It!
Jennifer ordered two pizzas to share
with her friends. She gives Jeff 3/8 of
the pizza and her girlfriends eat 7/8 of
the pizza. How much pizza will she
have left for herself?
2 - ½ - 1½ = ½
Closure
On a sticky note describe the
process of estimating with decimals
or fractions.
1.
Independent Practice
Estimate to the
nearest
Estimation
tenth..
23.49 + 34.78
2. Estimate
to the nearest
hundredth..
8. Amanda has
54.938 + 160.781
3. Estimate to the nearest dollar.. some 16 candy
$59.10 - $23.91
bars.
She
gives
4
Is 4 closer to 9, 9½, or
4. 9
and 3/4 bars to
Answer Key
1. 23.5 + 34.8 = 58.3
2. 54.94 + 160.78 = 215.72
3. $59 + $24 = $83
4. 9 1/2
5. 7
6. 6 + 3 + 8 1/2 = 171/2
7. 10 - 1 1/2 - 3 1/2 = 5
10? 7
8. 16 - 5 - 3 - 2 = 7
William,
3
and
3/9
4
Is
closer
to
6,
6
½,
or
7?
5. 6
5
3
7
1
6. 5 9 + 3 7 + 8 5
5
2
4
7. 9 3 - 1 7 - 3 8
=
=
to Orrin, and 2 and
1/11 to Athena.
How much does
she have left?