To express the number \(0.000000003\) in the form of \(a \times 10^n\), we can rewrite it as follows:
- First, convert the number to scientific notation:
\[ 0.000000003 = 3 \times 10^{-9} \]
In this case, \(a = 3\) and \(n = -9\).
Thus, the final answer is:
\[ 3 \times 10^{-9} \]