when estimating fractions you can use 2 different strategies. use compatible numbers… …when...
TRANSCRIPT
When estimating fractions you can use 2 different strategies.
Use Compatible Numbers…
…when multiplying a whole number and a fraction.
…when multiplying a mixed number and a fraction.
3765 x
3416 x3
5
When estimating fractions you can use 2 different strategies.
Use Compatible Numbers…
…when multiplying a whole number and a fraction.
…when multiplying a mixed number and a fraction.
3765 x
3416 x3
5
Use Rounding…
…when multiplying two mixed numbers.
…when multiplying a mixed number and a whole number.
1747 x2 9
10
5 x 2 12
56 41x
Best Strategy
ExampleType of Problem
Compatible Numbers
Whole Number X Fraction
56
x4156
x 4242 ÷ 6 =7 x 5 = 35
When estimating a product of a fraction and
a whole number, use compatible numbers.
Step 1:
Find the closest basic math fact to 6 and 41.
Step 2:
Rewrite the problem with the compatible numbers.
Step 3:
Divide the whole number by the denominator.
Step 4:
Multiply the quotient by the numerator.
7
≈35
57 x13 2
9
56 41x
Best Strategy
ExampleType of Problem
Compatible Numbers
Mixed Number X Fraction
Compatible Numbers
Whole Number X Fraction
57 x1357 x 14
14 ÷ 7 =2 x 5 = 10
When estimating a product of a
fraction and a mixed
number, use compatible numbers.
Step 1:
Find the closest basic math fact to 7 and 13 .
Step 2:
Rewrite the problem with the compatible numbers.
Step 3:
Divide the whole number by the denominator.
Step 4:
Multiply the quotient by the numerator.
2
≈1029
29
57 x13 2
9
56 41x
10 23 x3 1
9
Best Strategy
ExampleType of Problem
RoundMixed Number X Mixed Number
Compatible Numbers
Mixed Number X Fraction
Compatible Numbers
Whole Number X Fraction
1023
x3
Think:
23
12
VAdd 1 More!
11
x 3=33
19
Think:
19
12
V
Just Ignore!
When estimating a product of mixed numbers,
use rounding.
x4 34 7
57 x13 2
9
56 41x
10 23 x3 1
9
Best Strategy
ExampleType of Problem
RoundWhole Number X Mixed Number
RoundMixed Number X Mixed Number
Compatible Numbers
Mixed Number X Fraction
Compatible Numbers
Whole Number X Fraction
434
x7
Think:
34
12
VAdd 1 More!
5 x 7=35When
estimating a product of a mixed
number and a whole
number, use
rounding.
x4 34 7
57 x13 2
9
56 41x
10 23 x3 1
9
Best Strategy
ExampleType of Problem
RoundWhole Number X Mixed Number
RoundMixed Number X Mixed Number
Compatible Numbers
Mixed Number X Fraction
Compatible Numbers
Whole Number X Fraction
3230
25
x
25
x30 ÷ 5 =6 x 2 = 12
When estimating a product of a fraction and
a whole number, use compatible numbers.
Step 1:
Find the closest basic math fact to 5 and 32.
Step 2:
Rewrite the problem with the compatible numbers.
Step 3:
Divide the whole number by the denominator.
Step 4:
Multiply the quotient by the numerator.
6
≈12
838
x4
Think:
38
12
V
Just Ignore!
8 x 5=40
79
Think:
79
12
V
Add 1 More!
When estimating a product of mixed numbers,
use rounding.
56
x4156
x 4242 ÷ 6 =7 x 5 = 35
When estimating a product of a fraction and
a whole number, use compatible numbers.
Step 1:
Find the closest basic math fact to 6 and 41.
Step 2:
Rewrite the problem with the compatible numbers.
Step 3:
Divide the whole number by the denominator.
Step 4:
Multiply the quotient by the numerator.
7
≈35
Compatible numbers allow you to estimate quotients by changing the dividend and the divisor into a basic math fact.
4412 ÷ 3 =12 ÷ 3 =11 ÷ 311 ÷ 3
7742 ÷ 6 =42 ÷ 6 =40 ÷ 640 ÷ 6
4428 ÷ 7 =28 ÷ 7 =29 ÷ 729 ÷ 7
7756 ÷ 8 =56 ÷ 8 =55 ÷ 855 ÷ 8
111199 ÷ 9 =99 ÷ 9 =98 ÷ 998 ÷ 9
EstimatiEstimationon
Closest Basic Closest Basic Math FactMath Fact
Division Division ProblemProblem
Find you’re your number,
Look right next door
, just ignore,
or more, add one more.
12Four or less
Five12
723
Think:
23
12
V
Add 1 More!
8549
Think:
49
12
V
Just Ignore!
5
Less than