The given expression is:
[tex](5\text{ }\times100)+(6\times1)+(5\times\frac{1}{10})+(9\times\frac{1}{1000})[/tex]This can be simplified as:
[tex](500)+6+(\frac{5}{10}^{})+(\frac{9}{1000}^{})[/tex][tex]\begin{gathered} 500\text{ + 6 + 0.5+0.009} \\ =506.509 \end{gathered}[/tex]This can be expressed in standard form:
[tex]5.06509\times10^2[/tex]