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## Texas Go Math Grade 8 Module 2 Quiz Answer Key

**Texas Go Math Grade 8 Module 2 Ready to Go On? Answer Key**

**2.1 Scientific Notation with Positive Powers of 10**

**Write each number in scientific notation.**

Question 1.

2,000 ______________

Answer:

2,000 Given

2.0 Move the decimal point 3 places to the left. Remove the extra zeros.

1000 Divide the original number by the result from above.

10^{3} Write the answer as power of 10.

2.0 × 10^{3} Write the product of the results from the above.

2.0 × 10^{3}

Question 2.

91,007,500 ____________

Answer:

91,007,500 Given

91,007,500 Move the decimal point 7 places to the left. Remove the extra zeros.

10000000 Divide the original number by the result from above.

10^{7} Write the answer as power of 10.

9.10075 × 10^{7} Write the product of the results from the above.

9.10075 × 10^{7}

Question 3.

On average, the Moon’s distance from Earth is about 384,400 km. What is this distance in scientific notation? __________________

Answer:

**Write each number in standard notation.**

Question 4.

1.0395 × 10^{9} _______________

Answer:

Question 5.

4 × 10^{2} _______________

Answer:

Question 6.

The population of Indonesia was about 2.48216 × 10^{8} people in 2011. What is this number in standard notation? _______________

Answer:

**2.2 Scientific Notation with Negative Powers of 10**

**Write each number in scientific notation.**

Question 7.

0.02 _______________

Answer:

Question 8.

0.000701 ____

Answer:

0.000701 Given

7.01 Place the decimal point

4 Count the number of places the decimal point is moved

7.01 × 10^{4} Multiply 7.01 times a power of 10. Since 0.000701 is less than 1, the decimal point moves to the right and the exponent on 10 is negative.

**Write each number in standard notation.**

Question 9.

8.9 × 10^{-5} ______________

Answer:

8.9 × 10^{-5} Given

5 Use the exponent of the power of 10 to see how many places to move the decimal point.

places

0.000089 Place the decimal point Since you are going to write a number less than 8.9, move the decimal to the left. Add placeholder zeros if necessary.

0.000089

Question 10.

4.41 × 10^{-2} ______________

Answer:

4.41 × 10^{-2} Given

2 Use the exponent of the power of 10 to see how many places to move the decimal point.

places

0.0441 Place the decimal point Since you are going to write a number less than 4.41, move the decimal to the left. Add placeholder zeros if necessary.

0.0441

**Complete the table.**

Question 11.

Answer:

Question 12.

Answer:

Question 13.

Answer:

**Essential Question**

Question 14.

How is scientific notation used in the real world?

Answer:

**Texas Go Math Grade 8 Module 2 Mixed Review Texas Test Prep Answer Key**

**Selected Response**

Question 1.

Which of the following is the number 90 written in scientific notation?

(A) 90 × 10^{2}

(B) 9 × 10^{2}

(C) 90 × 10^{1}

(D) 9 × 10^{1}

Answer:

Question 2.

About 786,700,000 passengers traveled by plane in the United States in 2010. What is this number written in scientific notation?

(A) 7,867 × 10^{5} passengers

(B) 7.867 × 10^{2} passengers

(C) 7.867 × 10^{8} passengers

(D) 7.867 × 10^{9} passengers

Answer:

(C) 7.867 × 10^{8} passengers

Explanation:

786,700,000 Given

7.867 Move the decimal point 8 places to the left. Remove the extra zeros.

100000000 Divide the original number by the result from Step 1.

10^{8} Write the answer as power of 10.

7.867 × 10^{8} Write the product of the results from above

There are 7.867 × 10^{8} passengers

Question 3.

In 2011, the population of Mali was about 1.584 × 10^{7} people. What is this number written in standard notation?

(A) 1.584 people

(B) 1,584 people

(C) 15,840,000 people

(D) 158,400,000 people

Answer:

(C) 15,840,000 people

Explanation:

1.584 × 10^{7} Given

7 Use the exponent of the power of 10 to determine the number places to move the decimal point places

15,840,000 Place the decimal point. Since you are going to write a number greater than 1.584, move the decimal to the right. Add placeholder zeros if necessary.

There are

15,840,000 people

Question 4.

The square root of a number is between 7 and 8. Which could be the number?

(A) 72

(B) 83

(C) 51

(D) 66

Answer:

(C) 51

Explanation:

7 and 8 Given

49 and Find the squares of the number

64

Since the square root lies between

$7$ and $8$, the square of the number

lies between $49$ and $64$, hence it

could be $51$

Question 5.

Pilar is writing a number in scientific notation. The number is greater than ten million and less than one hundred million. Which exponent will Pilar use?

(A) 10

(B) 7

(C) 6

(D) 2

Answer:

Question 6.

Place the numbers in order from least to greatest.

0.24, 4 × 10^{-2}, 0.042, 2 × 10^{-4}, 0.004

(A) 2 × 10^{-4}, 4 × 10^{-2}, 0.004, 0.042, 0.24

(B) 0.004, 2 × 10^{-4}, 0.042, 4 × 10^{-2}, 0.24

(C) 0.004, 2 × 10^{-4}, 4 × 10^{-2}, 0.042, 0.24

(D) 2 × 10^{-4}, 0.004, 4 × 10^{-2}, 0.042, 0.24

Answer:

(D) 2 × 10^{-4}, 0.004, 4 × 10^{-2}, 0.042, 0.24

Explanation:

0.24, 4 × 10^{-2}, 0.042, 2 × 10^{-4}, 0.004

2.4 × 10^{-1} Express the numbers in scientific notation

4 × 10^{-2}

4.2 × 10^{-2}

2 × 10^{-4}

4 × 10^{-3}

2 × 10^{-4} Compare the power of 10 and if they are same

4 × 10^{-3} compare the first factor

4 × 10^{-2} Placed in the order from least to greatest

4.2 × 10^{-2}

2.4 × 10^{-1}

2 × 10^{-4}, 0.004, 4 × 10^{-2}, 0.042, 0.24 placed in the order from least to greatest

Question 7.

Which of the following is the number 1.0085 × 10^{-4} written in standard notation?

(A) 10,085

(B) 1.0085

(C) 0.00010085

(D) 0.000010085

Answer:

Question 8.

A human hair has a width of about 6.5 × 10^{-5} meter. What is this width written in standard notation?

(A) 0.00000065 meter

(B) 0.0000065 meter

(C) 0.000065 meter

(D) 0.00065 meter

Answer:

(C) 0.000065 meter

Explanation:

6.5 × 10^{-5} Given

5 Use the exponent of the power of 10 to see how many places to move the decimal point.

places

0.000065 Place the decimal point Since you are going to write a number less than 6.5, move the decimal to the left. Add placeholder zeros if necessary.

The width in standard notation is $0.000065$ meter

**Gridded Response**

Question 9.

Write 2.38 × 10^{-1} in standard form.

Answer: