Page 12 - Math Course 2 (Book 1)

Standard Form and Scientif c Notation

MO. 1 - L1b

Comparing Numbers in
Scientif c Notation Answer So, Pluto is about 1.0 ×102 or 100
times farther from the Sun than
Mercury is.

Let’s Begin Check
Use estimation to check the reasonableness of
the results.
REAL WORLD EXAMPLE

Example

REAL WORLD EXAMPLE
SPACE
The table shows the planets and
their distances from the Sun. Example
Estimate how many times farther
Pluto is from the Sun than Mercury is
from the Sun.
SPACE
The diameters of Mercury, Saturn,
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Planet Distance from the sun (km) and Pluto are 4.9 × 10 kilometers,
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1.2 × 10 kilometers, and 2.3 × 10
Mercury 5.80 x 10 7 kilometers, respectively. List the
planets in order of increasing diameter.
Venus 1.03 x 10 8
Earth 1.55 x 10 8 First, order the numbers according to their
Mars 2.28 x 10 8 exponents.

Jupiter 7.78 x 10 8 Then, order the numbers with the same exponent
Saturn 1.43 x 10 9 by comparing the factors.
Uranus 2.87 x 10 9
Neptune 4.50 x 10 9
Pluto 5.90 x 10 9 Mercury and Pluto Saturn

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Step 1 4.9 × 10 < 1.2 × 10
Explore
The distance from the Sun to Pluto is 5.90 × 109 2.3 × 10 3
km and the distance from the Sun to Mercury is
5.80 × 107 km.
Plan Step 2 2.3 × 10³ < 4.9 × 10³ Compare the
To f nd how many times farther Pluto is from the factors: 2.3 < 4.9.
Sun than Mercury is from the Sun, f nd the ratio of
Pluto’s distance to Mercury’s distance. Since you Pluto Mercury
are estimating, round the distance 5.90 × 109 to
6.0 × 109 and round the distance 5.80 × 107 to 6.0
× 107. Answer So, the order is Pluto, Mercury,

6.0 x 10 9 and Saturn
Solve = 1.0 x 10 2
6.0 x 10 7

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