1. Rounding Decimals
Unit 3.2
Pages

2. Order the numbers from LEAST to GREATEST?
Warm Up
Problems
Order the numbers from LEAST to GREATEST?
18.74, 18.7, 18.47
9.06, 9.66, 9.6, 9.076
3.072
6.158
18.47, 18.7, 18.74
9.06, 9.076, 9.6, 9.66
Three and seventy two thousandths
Six and one hundred fifty eight thousandths
Write in words

3. Estimating Decimals.
Objective: Students will be able to estimate decimal sums, differences, products and quotients by clustering, using place value, grouping and using front/back end estimation.

4. Wholes Parts of the Whole
A decimal helps us to see what numbers are WHOLE numbers, and what numbers are PARTS OF THE WHOLE.
Wholes
Parts of the Whole

5. Definitions Clustering: Rounding numbers to the same value (amount).
Front-End Estimation: Use the whole numbers in the decimals to estimate values (amounts).

6. Let’s review some definitions that
we should already know.
Sum
Difference
Product
Quotient
Addition
Subtraction
Multiplication
Division

7. We use decimal estimation in real word situations?
Can you think of any?

8. We will be solving equations with decimals using a few different strategies:
Place
Value
Front
End
Comparable
Numbers
Clustering

9. Estimate numbers with decimals by
rounding to the indicated place value.
Place
Value
ONES
Look at the digit to the right of your place value.
If it is a 5 or greater round up one number.
If it is less that 5 round down by adding zero’s.
4 + 6 = 10

10. #2.
Estimate numbers with decimals by
rounding to the indicated place value.
Place
Value
tenths
2.746 – 0.866
Look at the digit to the right of your place value.
If it is a 5 or greater round up one number.
If it is less that 5 round down by adding zero’s.
2.7 – = about 1.8

11. #3.
Estimate numbers with decimals by
rounding to the indicated place value.
Place
Value
ones
Look at the digit to the right of your place value.
If it is a 5 or greater round up one number.
If it is less that 5 round down by adding zero’s.
= about 12

12. We will be solving equations with decimals using a few different strategies:
Place
Value
Front
End
Comparable
Numbers
Clustering

13. When numbers are close to the same amount, you can use
Someone who weighs about 90 pounds can burn the following calories:
Clustering
Activity
Calories
Estimation
Bicycling
198.45
Playing Ice Hockey
210.60
Rowing
224
Water Skiing
194.4
200.00
When numbers are close to
the same amount, you can use
clustering: changing all amounts to same value.

14. Ella will run about _____ total miles .
#1.
Ella runs three days a week. She ran 3.62 miles on Monday, 3.8 miles on Wednesday, and 4.3 miles on Friday. About how any miles did she run on last week?
Clustering
Days of the Week
Miles
Estimation
Monday
3.62
Wednesday
3.8
Friday
4.3
4.00
Ella will run about _____ total miles . 12

15. Estimate Each Product or Quotient
Compatible
Numbers
Compatible numbers are
close to the numbers that are in the problem, and can be helpful when you are solving estimations using MENTAL MATH.
26.76 x 2.93
26.76 x 2.93
25 x 3
about75

16. Estimate Each Product or Quotient
Compatible
Numbers
Compatible numbers are
close to the numbers that are in the problem, and can be helpful when you are solving estimations using MENTAL MATH.
40 / 20
about2

17. Estimate Each Product or Quotient#6
Estimate Each Product or Quotient
Compatible
Numbers
Compatible numbers are
close to the numbers that are in the problem, and can be helpful when you are solving estimations using
MENTAL MATH.
__ /__
About _______

18. Estimate Each Product or Quotient#7
Estimate Each Product or Quotient
Compatible
Numbers
Compatible numbers are
close to the numbers that are in the problem, and can be helpful when you are solving estimations using
MENTAL MATH.
14.75 x 7.89
__ /__
About _______

19. Front and Back End Estimation
When using the Front End Estimation Strategy we look at the WHOLE number, in front of the decimal and estimate for that number before adding or subtracting the amounts.
Front and Back End Estimation 9 22
+ 8 39
9.99
22.89

20. Front and Back End Estimation
When using the Back End Estimation Strategy we look at the WHOLE number, in back of the decimal and estimate for that number before adding or subtracting the amounts.
Front and Back End Estimation
9.99
22.89
1.00
+ .50
2.50

21. We can now take the two amounts, add them together and find the
9.99
22.89
We can now take the two amounts, add them together and find the
RANGE
For the sum.
Front and Back End Estimation
The range is 39 to 41.50

22. Find the range for each sum.
#9.
Find the range for each sum.
Front and Back End Estimation
8.00
31.00
7.00
46.00
7.8
31.39
1.00
.40
2.40
The range is about 46 to 48.40

23. Find the range for each sum.
#10.
Find the range for each sum.
Front and Back End Estimation
14.00
5.00
22.00
41.00
14.27
5.4
+21.86
.30
.40
1.00
1.70
The range is about 41 to 42.70

24. 12-26 12-19 3.2 Homework Page 106-107 Due: Thursday
Mrs. Saucedo’s class
12-19

25. Round to the tenth place value
Round to the nearest whole place
7.305 – 3
4.5
Estimate each product or quotient
Estimate each product or quotient
6.75 x 1.82 14 9