Answer:
1/625 0r 0.0016 is the product of the given expression.
Explanation:
Here, The given expression, 5^{-1} \times 5^-3
We can write, 5^-1 \times 5^-3=\frac{5^{-1}}{5^3} ( because we can write a^m=1/a^{-m})
⇒5^-1 \times 5^-3=\frac{1}{5^1\times 5^3}
⇒5^-1 \times 5^-3=\frac{1}{5^{1+3}} ( because a^m\times a^n=a^{m+n})
⇒5^-1 \times 5^-3=\frac{1}{5^{4}}
⇒5^-1 \times 5^-3=\frac{1}{625}=0.0016