Chapter 2 - Section 2.5 - Powers of 10 - Exercises - Page 122: 15

$\frac{1}{10^4}$

$(\frac{10^6}{10^8})^2\longrightarrow$ to raise a power to a power, multiply the exponents $=\frac{10^{12}}{10^{16}}^\longrightarrow$ to divide powers subtract the exponents $=10^{12-16}$ $=10^{-4}\longrightarrow$ express the result using a positive exponent $=\frac{1}{10^4}$