1. Unit 3, Lesson 15 Round and Estimate with Decimals

2. Task-Round to nearest whole number!
Round 4.7 to the nearest whole number

3. On this number line, 4.7 is between which two whole numbers?
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5.0
On this number line, 4.7 is between which two whole numbers?
What number is exactly halfway between 4 and 5?
Is 4.7 to the right or to the left of 4.5?
Is 4.7 closer to 4 or closer to 5?
What is 4.7 rounded to the nearest whole number?

4. Why is 4 NOT the correct answer?
Because 4.5 is exactly halfway between 4 and 5
4.7 is to the right of 4.5
4.5 is closer to 5 than to 4
Therefore; 4.7 rounds to 5
4.0
4.5
5.0

5. 4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5.0
How can this number line be used to round 4.4 to the nearest whole number?

6. 4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5.0
How can this number line be used to round 4.5 to the nearest whole number?
A number that is exactly halfway between two numbers always rounds up.

7. Task-Round to nearest tenth!
Round 1.62 to the nearest tenth

8. What is 1.62 rounded to the nearest tenth?
1.7
1.60
1.61
1.62
1.63
1.64
1.65
1.66
1.67
1.68
1.69
1.70
What is 1.62 rounded to the nearest tenth?
Use what you know about rounding to the nearest whole number to explain why 1.62 rounds to 1.6.

9. What is 1.68 rounded to the nearest tenth?
1.7
1.60
1.61
1.62
1.63
1.64
1.65
1.66
1.67
1.68
1.69
1.70
What is 1.68 rounded to the nearest tenth?
Use what you know about rounding to the nearest whole number to explain why 1.68 rounds to 1.7.

10. What is 1.65 rounded to the nearest tenth?
1.7
1.60
1.61
1.62
1.63
1.64
1.65
1.66
1.67
1.68
1.69
1.70
What is 1.65 rounded to the nearest tenth?
A number that is exactly halfway between two numbers always rounds up.

11. Recall Decimal Place Value
A decimal number in tenths has how many digits to the right of the decimal point?
How many digits to the right of the decimal point does a decimal number in hundredths have?
A decimal number in thousandth has how many digits to the right of the decimal point?

12. 8.057 What digit is in the tenths place?
What digit is in the thousandths place?
What digit is in the ones place?
What digit is in the hundredths place?
Suppose we round to the nearest whole number. Why is the digit in the tenths place of our number important?

13. 8.057
Explain why the digit in the tenths place of tells us that the number rounds to 8 instead of 9.
What digits would have to be in the tenths place of our number for it to round to 9 instead of 8?

14. 3.6405 Name the digit in the thousandths place.
Name the digit in the ten thousandths place.
Explain how to round to the nearest thousandth.

15. Open your hard back book to page 121

16. Determine Reasonable Answers
Remember the importance of checking your work
Describe different methods they have used in the past to check answers.

17.
How can rounding to the nearest whole number help make a reasonable estimate of the exact sum?
A reasonable estimate is 14 because rounds to 8, rounds to 6.
6 + 8 = 14

18. Estimating Differences
4.107 – 3.288
Estimate the difference by rounding to the nearest whole number

19. Open your hard back book to page 122