**Lesson 64**

**Objective**

: Identify and understand the value of the decimal places tenths and hundredths.

: Identify and understand the value of the decimal places tenths and hundredths.

Math 4 Today

Powers of 10

The whole-number place values can be represented by the powers of 10.

10 10 10 10

1000 100 10 1

Moving from left to right, the exponent decreases by 1 for each place.

10 10 10 10 10 10 10

1000 100 10 1 1 1 1

10 100 1000

3

2

3

2

-1

-2

-3

Example 1

What combination of dollars, dimes, and pennies makes $4.65 using the fewest bills and coins possible?

Example 2

What is the place value of the 4 in $6.24?

Example 3

Is $3.67 closer to $3.60 or to $3.70?

Example 4

On his way home from work, T'Vaughn stopped at the supermarket and purchased carrots for $1.66, broccoli for $3.42, and cauliflower for $2.55. What is a reasonable estimate of the cost of the vegetables?

Lesson Practice

What is the place value of the 5 in each of these numbers?

a) $25.60 b) $54.32 c) $12.75 d) $21.50

e) What combination of dollars, dimes, and pennies makes $3.84 using the fewest bills and coins possible?

f) Is $12.63 closer to $12.60 or to $12.70?

g) Is $6.08 closer to $6.00 or to $6.10?

h) Teresa purchased three notebooks for $1.49 each. What is a reasonable estimate of the total cost of the notebooks? Explain your answer.

i) 512 52= j) 412 97= k) 237 83=

**Reflection:**

A microscope has a setting that magnifies an object so that it appears 100 times as large when viewed through the eyepiece. If a tiny insect is 0.095 cm long, how long will the insect appear in centimeters through the microscope? Explain how you know.

A microscope has a setting that magnifies an object so that it appears 100 times as large when viewed through the eyepiece. If a tiny insect is 0.095 cm long, how long will the insect appear in centimeters through the microscope? Explain how you know.

1) 2 2) Write 75,854 in expanded form.

5

- 1

4

3) Find the area of the rectangle. 4) Write an expression for the

calculation

subtract 12 doubled

3/10 ft.

from 132.

3 ft.

1

0

1

0

Complete the patterns.

a. 0.03 0.3 ____ 30 _____ ______

b. 6,500,000 65,000 ______ 6.5 _______

c. ____ 9,430 ______ 94.3 9.43 ______

d. 999 9990 99,900 ______ ______ ______

e. _____ 7.5 750 75,000 ______ ______

f. Explain how you found the unknown numbers in set (b). Be sure to include your reasoning about the number of zeros in your numbers and how you placed the decimal.

g. Explain how your found the unknown numbers in set (d).. Be sure to include your reasoning about the number of zeros in your numbers and how you placed the decimal.

Shaunnie and Marlon missed the lesson exponents. Shaunnie incorrectly wrote 10 = 50 on her paper, and Marlon incorrectly wrot 2.5 x 10 = 2.500 on his paper.

a. What mistake has Shaunnie made? Explain using words, numbers, or pictures why her thinking is incorrect and what she needs to do to correct her answer.

b. What mistake has Marlon made? Explain using words, numbers, or pictures why his thinking is incorrect and what he needs to do to correct his answer.

5

2

1)Write the following in exponential form ( e.g. 100 = 10 )

a. 10,000 = ______ d. 100 x 100 =_______

b. 1,000 = _______ e. 1,000,000 = ________

c. 10 x 10 = ______ f. 1,000 x 1,000 = _______

2) Write the following in standard form ( e.g. 5 x 10 = 500 )

a. 9 x 10 = _______ e. 4.025 x 10 = _______

b. 39 x 10 = ______ f. 40.25 x 10 = _______

c. 7,200 10 = _______ g. 72.5 10 = _______

d. 7,200,000 10 = ______ h. 7.2 10 = _______

3) Think about the answers to Problem 2 (a-d). Explain the pattern used to find an answer when you multiply and divide a whole number by a power of 10.

4) Think about the answers to Problem 2 (e-h). Explain the pattern used to place the decimal in the answer when you multiply and divided a whole number by a power of 10.

2

2

3

3

4

4

2

2

3

2