Learn to estimate sums and differences of fractions and mixed numbers.

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Learn to estimate sums and differences of
fractions and mixed numbers.
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You can estimate fractions by rounding to 0, ,
or 1.
1
3
1
3
1
7
5
1
The fraction is halfway between and 1,
but we usually round up. So the fraction
rounds to 1.
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You can round fractions by comparing the
numerator and denominator.
1
0


closer to 1 Each numerator is about the
same as the denominator, so the fractions are
close to 1.
closer to 0 Each numerator is much less
than half the denominator, so the fractions are
close to 0.
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Additional Example 1A Estimating
Fractions Estimate each sum or difference by
rounding to 0, , or 1.
Think rounds to 1 and rounds to .


1 1
is about 1 .
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Additional Example 1B Estimating
Fractions Estimate each sum or difference by
rounding to 0, , or 1.

Think rounds to 1 and rounds to 1.
1 1 0
is about 0.
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Check It Out Example 1A Estimate each sum or
difference by rounding to 0, , or 1.

Think rounds to 1 and rounds to .


1 1
is about 1 .
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Check It Out Example 1B Estimate each sum or
difference by rounding to 0, , or 1.

Think rounds to 1 and rounds to 0.
1 0 1
is about 1.
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You can also estimate by rounding mixed numbers.
You compare each mixed number to the two nearest
whole numbers and the nearest . Does 10
round to 10, 10 , or 11?
10 10 10
11

10 10 10 10 10
10 10
The mixed number 10 rounds to 10 .
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Additional Example 2A Sports Application The
table shows the distances Tosha walked. About
how far did Tosha walk on Tuesday and Thursday?

5 5 10
She walked about 10 miles on Tuesday and Thursday.
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Additional Example 2B Sports Application The
table shows the distances Tosha walked. About
how much farther did Tosha walk on Sunday than
Thursday?
8 4
9 5 4
She walked about 4 miles farther on Sunday than
on Thursday.
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Additional Example 2C Sports Application The
table shows the distances Tosha walked. Estimate
the total distance Tosha walked on
Thursday, Saturday, and Sunday.
4 6 8
5 6 9 20
She walked about 20 miles on Thursday,
Saturday, and Sunday.
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Check It Out Example 2A The table shows the
distances Jerry roller skated. About how far did
Jerry skate on Tuesday and Sunday?
3 2
3 3 6
He roller skated about 6 miles on Tuesday and
Sunday.
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Check It Out Example 2B The table shows the
distances Jerry roller skated. About how much
farther did Jerry skate on Saturday than
Tuesday?
8 3
8 3 5
He roller skated about 5 miles farther on
Saturday than Thursday.
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Check It Out Example 2C The table shows the
distances Jerry roller skated. Estimate the
total distance Tosha walked on Tuesday,
Thursday, and Sunday.
3 6 3 12
He roller skated about 12 miles on Tuesday,
Thursday, and Sunday.
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Lesson Quiz Part I
Estimate each sum or difference by rounding to 0,
, or 1.
1. 2. 3. 4.
0
1
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Lesson Quiz Part II
5. The conservation club picked up trash along
the road for three weeks. The table shows the
number of pounds of trash they collected. About
how many pounds did they collect in weeks 2 and 3?
about 37 pounds