Evaluate: (4.2 * 10^2)/(2.1 * 10^3)

Expression: $\left( 4.2 \times {10}^{2} \right)\div\left( 2.1 \times {10}^{3} \right)$

Write the division as a fraction

$\frac{ 4.2 \times {10}^{2} }{ 2.1 \times {10}^{3} }$

Separate the fraction into $2$ fractions

$\frac{ 4.2 }{ 2.1 } \times \frac{ {10}^{2} }{ {10}^{3} }$

Divide the numbers

$2 \times \frac{ {10}^{2} }{ {10}^{3} }$

Divide the terms with the same base by subtracting their exponents

$2 \times {10}^{2-3}$

Calculate the difference

$\begin{align*}&2 \times {10}^{-1} \\&0.2\end{align*}$