Answer
$\{3.5\times10^{6},3.6\times10^{6},2.1\times10^7,2.5\times10^{7}\}$
Work Step by Step
To order numbers in scientific notation, we first must write each number in scientific notation.
$\{2.5\times10^{7},2.1\times10^7,3.5\times10^{6},3.6\times10^{6}\}$
Then, we order the numbers first by their powers of $10$. For numbers with the same power of $10$, we arrange them by their decimal parts.
$\{3.5\times10^{6},3.6\times10^{6},2.1\times10^7,2.5\times10^{7}\}$
