Write the numbers without the powers of ten.

a) [[$ \text{5.12} \cdot 10^{-5} $]] =
b) [[$ \text{1.4} \cdot 10^{-9} $]] =
c) [[$ \text{6.1} \cdot 10^{-16} $]] =
d) [[$ \text{2.5} \cdot 10^{-25} $]] =