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Word Problems Involving Exponents Study Guide (page 2)

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Updated on Apr 25, 2014

Converting to and From Scientific Notation and Standard Form

Scientific Notation

Scientific notation is used to write very large and very small numbers in a more efficient manner. This form uses a number between one and ten and multiplies it by a power of 10. For example, the number 3,000,000,000 is written as 3 × 109 in scientific notation.

Converting From Standard Form to Scientific Notation

To change a number from standard form into scientific notation, take the first non-zero digit and place a decimal point to its right to form a value between 1 and 10. Then, multiply by a power of 10, where the exponent is the number of places the decimal point moves.

For example, to write the number 4,500,000 in scientific notation, use the digits 4 and 5 and write the decimal 4.5. Because the decimal point needs to move six places to the left to be between the 4 and 5, the exponent is 6. The scientific notation is 4.5 × 106.

Converting From Scientific Notation to Standard Form

To convert to standard form from scientific notation, reverse the process just explained. Write the value between one and 10, but move the decimal point as according to the exponent.

For example, for the value 3.42 × 10–4, first write the number 3.42. Then, move the decimal to the right if the exponent is positive or to the left if the exponent is negative. Use zeros as placeholders when necessary. Since this exponent is –4, move the decimal four places to the left. The standard form is 0.000342.

 

Tip:

When you are converting from standard form to scientific notation, numbers greater than one have a positive exponent and numbers less than one have a negative exponent.

Word Problems with Exponents

The word problems in this section involve using the properties of exponents. Use the information in this lesson and the problem solving steps to solve each one.

Example 1

What is the product of 105× 108?

Read and understand the question. This question is looking for the product of two values that have the same base.

Make a plan. Add the exponents to find the solution.

Carry out the plan. The problem becomes 105× 108= 105 + 8 = 1013.

Check your answer. To check your answer, divide the product by one of the factors that was multiplied in the question.

Because this was the other factor, this answer is checking.

Example 2

What is the quotient of 165and 163?

Read and understand the question. This question is looking for the quotient of two values that have the same base.

Make a plan. Subtract the exponents to find the solution.

Carry out the plan. The problem becomes

    • = 162

Check your answer. To check your answer, multiply the quotient by the factor 163.

    • 162× 163= 162 + 3
    • = 165

Because this was the first value given in the question, this answer is checking.

Example 3

A garbage company collects 64,000,000 pounds of garbage per year. What is this amount expressed in scientific notation?

Read and understand the question. This question is looking for the scientific notation when the standard form is given.

Make a plan. Use the first non-zero digit and a decimal point to form a number between one and 10, and then write this number multiplied by a power of 10. The exponent is the number of places the decimal point moves from the end of the number to between the 6 and the 4.

Carry out the plan. Write the decimal 6.4. Next, multiply this value by 107because the decimal moves 7 places to the left. The scientific notation is 6.4 × 107.

Check your answer. To check your answer, put this number back into standard form. Take the decimal 6.4 and move the decimal 7 places to the right. Add zeros as placeholders where necessary. The number becomes 64,000,000. This answer is checking.

Find practice problems and solutions for these concepts at Word Problems Involving Exponents Practice Questions.

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