Digits, Grade 8, Volume 2, Homework Helper

### 15-5: TEKS Practice

• 1. Add 3.6 × 107 + 5.1 × 107 and write your answer in scientific notation.

• 2. Subtract 8.4 × 108 − 3.2 × 108 and write your answer in scientific notation.

• 3. Think About the Process

• a. Describe the procedure for multiplying two numbers in scientific notation.

• A. Multiply the first factors, then add the exponents of the powers of 10.

• B. Multiply the first factors, then subtract the exponents of the powers of 10.

• C. Add the first factors, then multiply the exponents of the powers of 10.

• D. Add the first factors, then add the exponents of the powers of 10.

• b. Find the product of (8.1×10−5)(6×10−5).

• 4. Simplify the expression (7×10−6)(7×10−6). Write the answer in scientific notation.

• 5. A certain star is 4.3×102 light years from the Earth. One light year is about 5.9×1012 miles. How far from the earth (in miles) is the star?

• 6. Divide fraction 7.2 times , 10 super negative 8 end super , over 3 times , 10 super negative 2 end super end fraction . . Express your answer in scientific notation.

• 7. Estimation You are given the following expression and asked to find the sum.

3.4×104+2.58×105

• a. Round each decimal to the nearest integer. Use these rounded numbers to estimate the sum.

• A. 3×104

• B. 6×105

• C. 3×105

• D. 6×104

• 8. In one year, the total amount of garbage generated in a certain country was 6.958×1010 pounds. In the same year, the country's population was 4.57×106 people. Determine the pounds of garbage produced per person in that country in one year.

• 9. Think About the Process

• a. Find the quotient of the first factors of fraction 2.2 times , 10 to the fifth , over 4.4 times , 10 super negative 3 end super end fraction . . What do you notice?

• A. The quotient of the first factors is greater than 1 but less than 10.

• B. The quotient of the first factors is greater than 10.

• C. The quotient of the first factors is less than 1.

• b. Find fraction 2.2 times , 10 to the fifth , over 4.4 times , 10 super negative 3 end super end fraction . .

• c. How does this affect the exponent of the quotient?

• 10. Writing Subtract 2.4×105−5×104. Describe the process of rewriting the numbers in this problem with the same power of 10.

• 11.

• a. Reasoning Subtract 3.95×10−2−3.36×10−2 and write your answer in scientific notation.

• b. Can you write the result using different exponents? Explain.

• 12. On a certain planet, Continent X has area 6.23×106 square miles and Continent Y has area 6.36×106 square miles. Which continent is larger? By how many square miles is its area greater?

• A. The area of Continent X is ▪ square miles greater than the area of Continent Y.

• B. The area of Continent Y is ▪ square miles greater than the area of Continent X.

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