а)
\[
2^5 \cdot 2^3 = 2^{5+3} = 2^8 = 256
\]
б)
\[
4^{-21} \cdot 4^{23} = 4^{-21+23} = 4^2 = 16
\]
в)
\[
5^{11} : 5^{14} = 5^{11-14} = 5^{-3} = \frac{1}{5^3} = \frac{1}{125}
\]
г)
\[
3^{-9} : 3^{-43} = 3^{-9 - (-43)} = 3^{-9+43} = 3^{34}
\]
д)
\[
(10^{-3} \cdot 10^{-4})^{-1} = (10^{-3-4})^{-1} = (10^{-7})^{-1} = 10^{7}
\]
е)
\[
(0.2^{-5})^3 \cdot 0.2^{-6} = 0.2^{-5 \times 3} \cdot 0.2^{-6} = 0.2^{-15} \cdot 0.2^{-6} = 0.2^{-15-6} = 0.2^{-21}
\]