10.7 Exercises
Help with Homework
1. WRITING Describe how to subtract two numbers written in scientific notation
with the same power of 10.
2. NUMBER SENSE You are multiplying two numbers written in scientific notation
with different powers of 10. Do you have to rewrite the numbers so they have the
same power of 10 before multiplying? Explain.
6)=3
9+(- 3)=
3+(- 9)=
4+(- =
1)
9+(-
Evaluate the expression using two different methods. Write your answer in
scientific notation.
3.
5.
( 2.74 × 107 ) + ( 5.6 × 107 )
( 5.1 × 105 ) × ( 9.7 × 105 )
4.
6.
( 8.3 × 106 ) + ( 3.4 × 105 )
( 4.5 × 104 ) × ( 6.2 × 103 )
Find the sum or difference. Write your answer in scientific notation.
1
7.
9.
11.
13.
( 2 × 105 ) + ( 3.8 × 105 )
( 9.2 × 108 ) − ( 4 × 108 )
( 7.8 × 107 ) − ( 2.45 × 106 )
( 9.7 × 106 ) + ( 6.7 × 105 )
8.
10.
12.
14.
( 6.33 × 10−9 ) − ( 4.5 × 10−9 )
( 7.2 × 10−6 ) + ( 5.44 × 10−6 )
( 5 × 10−5 ) + ( 2.46 × 10−3 )
( 2.4 × 10−1 ) − ( 5.5 × 10−2 )
15. ERROR ANALYSIS Describe and correct the error in finding the sum of the numbers.
✗
( 2.5 × 109 ) + ( 5.3 × 108 ) = (2.5 + 5.3) × ( 109 × 108 )
= 7.8 × 1017
Find the product or quotient. Write your answer in scientific notation.
2
3 16. 5 × ( 7 × 107 )
18.
20.
22.
( 1.2 × 10−5 ) ÷ 4
( 3.6 × 107 ) ÷ ( 7.2 × 107 )
( 6.5 × 108 ) × ( 1.4 × 10−5 )
17.
19.
21.
23.
( 5.8 × 10−6 ) ÷ ( 2 × 10−3 )
( 5 × 10−7 ) × ( 3 × 106 )
( 7.2 × 10−1 ) × ( 4 × 10−7 )
( 2.8 × 104 ) ÷ ( 2.5 × 106 )
24. MONEY How many times greater is the thickness of a dime than the
thickness of a dollar bill?
Thickness â 0.135 cm
452
Chapter 10
Thickness â 1.0922 ñ 10Ź2 cm
Exponents and Scientific Notation
Evaluate the expression. Write your answer in scientific notation.
25. 5,200,000 × ( 8.3 × 102 ) − ( 3.1 × 108 )
26.
( 9 × 10−3 ) + ( 2.4 × 10−5 ) ÷ 0.0012
27. GEOMETRY Find the perimeter of the rectangle.
28. BLOOD SUPPLY A human heart pumps about
7 × 10−2 liter of blood per heartbeat. The average
human heart beats about 72 times per minute.
How many liters of blood does a heart pump
in 1 year? in 70 years? Write your answers in
scientific notation. Then use estimation to
justify your answers.
0.000074 cm
0.00007
0.000032 cm
4.26 cm
Area â 5.612 ñ 1014 cm2
9.2 ñ 107 cm
Not drawn to scale
29. DVDS On a DVD, information is stored on bumps that spiral
around the disk. There are 73,000 ridges (with bumps) and
73,000 valleys (without bumps) across the diameter of the
DVD. What is the diameter of the DVD in centimeters?
30. PROJECT Use the Internet or some other reference to find
the populations and areas (in square miles) of India, China,
Argentina, the United States, and Egypt. Round each
population to the nearest million and each area to the
nearest thousand square miles.
a. Write each population and area in scientific notation.
b. Use your answers to part (a) to find and order the
population densities (people per square mile) of each
country from least to greatest.
31.
Albert Einstein’s most famous equation is E = mc 2, where E is the
energy of an object (in joules), m is the mass of an object (in kilograms), and
c is the speed of light (in meters per second). A hydrogen atom has 15.066 × 10−11
joule of energy and a mass of 1.674 × 10−27 kilogram. What is the speed of light?
Write your answer in scientific notation.
Find the cube root. (Section 7.2)
3—
32. √−729
33.
√
3
—
1
512
—
35. MULTIPLE CHOICE What is the volume of
the cone? (Section 8.2)
A 16π cm3
○
B 108π cm3
○
C 48π cm3
○
D 144π cm3
○
Section 10.7
√−
—
34.
3
125
343
—
4 cm
9 cm
Operations in Scientific Notation
453