Chapter 4 - Review Exercises - Page 316: 24

$7.65\times10^{-8}$

Numbers in the scientific notation take the form $a\times10^n$ where $1\le a\lt10$ and $n$ is an integer. Hence, in scientific notation, the given expression, $ 0.0000000765 ,$ is equivalent to \begin{array}{l}\require{cancel} 7.65\times10^{-8} .\end{array}