Answer
$\displaystyle \frac{3}{8}=0.375$,
by expanding the fraction, or
by long division.
Work Step by Step
One way to do this is to expand the fraction so its denominator is 1000:
$\displaystyle \frac{3}{8}=\frac{3\times 125}{8\times 125}=\frac{375}{1000}=0.375.$
Another way is to perform long division, $3.000\div 8.$
The quotient is $0.375$