Fundamentals of Mathematics, 2008a

480 CHAPTER 8. TECHNIQUES OF ESTIMATION
8.2.2.7 Sample Set D
Example 8.5
Estimate the quotient: 153 ÷ 17.
Notice that 153 is close to 150,
}{{}
two nonzero
digits
The quotient can be estimated by 150 ÷ 15 = 10.
Thus, 153 ÷ 17 is about 10. In fact, 153 ÷ 17 = 9.
Example 8.6
Estimate the quotient: 742,000 ÷ 2,400.
and that 17 is close to 15.
}{{}
two nonzero
digits
Notice that 742,000 is close to 700, 000 , and that 2,400 is close to
} {{ }
2, 000.
} {{ }
one nonzero
one nonzero
digit
digit
The quotient can be estimated by 700,000 ÷ 2,000 = 350.
Thus, 742,000 ÷ 2,400 is about 350. In fact, 742,000 ÷ 2,400 = 309.16.
8.2.2.8 Practice Set D
Exercise 8.2.10 (Solution on p. 505.)
Estimate the quotient: 221 ÷ 18.
Exercise 8.2.11 (Solution on p. 505.)
Estimate the quotient: 4,079 ÷ 381.
Exercise 8.2.12 (Solution on p. 505.)
Estimate the quotient: 609,000 ÷ 16,000.
8.2.2.9 Sample Set E
Example 8.7
Estimate the sum: 53.82 + 41.6.
Notice that 53.82 is close to 54,
}{{}
two nonzero
digits
The sum can be estimated by 54 + 42 = 96.
and that 41.6 is close to 42.
}{{}
two nonzero
digits
Thus, 53.82 + 41.6 is about 96. In fact, 53.82 + 41.6 = 95.42.
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