# How many deciliters are in 500 mL?

$5 \cdot \text{decilitres}$
$1 \cdot \text{decilitre}$ $=$ ${10}^{- 1} L$.
$500 \cdot m L$ $=$ $500 \times {10}^{-} 3 \cdot L \times 10 \cdot \mathrm{dL} \cdot {L}^{-} 1$ $=$ ??dL