#### Answer

$\frac{1}{10},\frac{1}{100},\frac{1}{1000},\frac{1}{10000}$

#### Work Step by Step

$a_n = \frac{1}{10^n}$
First four terms are $a_1, a_2, a_3$, and $a_4$.
$a_1 = \frac{1}{10^1} = \frac{1}{10}$
$a_2 = \frac{1}{10^2} = \frac{1}{100}$
$a_3 = \frac{1}{10^3} = \frac{1}{1000}$
$a_4 = \frac{1}{10^4} = \frac{1}{10000}$