\[2 = 2^{1};\]
\[8 = 2^{3};\]
\[32 = 4 \cdot 8 = 2^{2} \cdot 2^{3} = 2^{2 + 3} = 2^{5};\]
\[128 = 32 \cdot 4 = 2^{5} \cdot 2^{2} =\]
\[= 2^{5 + 2} = 2^{7};\]