0,242/0,238 =

$$\frac{0.2^{42}}{0.2^{38}} = 0.2^{42-38} = 0.2^4 = 0.2 \cdot 0.2 \cdot 0.2 \cdot 0.2 = 0.0016$$.

Ответ: $$0.0016$$