第9章 9.10

(1)

$1.259 \times 1.995 = 10^{0.1} \times 10^{0.3} = 10^{0.4} = 2.512$

(2)

$1.585^3 = (10^{0.2})^3 = 10^{0.6} = 3.981$

(3)

$125.9 \times 39.81 = 1.259 \times 100 \times 3.981 \times 10 = 10^{0.1} \times 10^{0.6} \times 10^3 = 10^{0.7} \times 10^3 = 5.012 \times 10^3 = 5012$

(4)

$0.05012^2 \div 0.002512^3 = (5.012 \div 100)^2 \div (2.512 \div 1000)^3 = (5.012)^2 \div (2.512)^3 \times 10^5$

$= (10^{0.7})^2 \div (10^{0.4})^3 \times 10^5 = 10^{0.2} \times 10^5 = 1.585 \times 10^5 = 158500$