\(10^{-n}=0.\underbrace{00...01}_{n}\\\\7\times10^{-4}=7\times0.0001=0.0007\\----------------\\a.\ 8\times10^{-4}=8\times0.0008=0.0008\leftarrow \huge\boxed{greater}\\\\b.\ 9\times10^{-5}=9\times0.00001=0.00009 \ \textless \ 0.0007\\\\c.\ 4\times10^{-4}=4\times0.0001=0.0004 \ \textless \ 0.0007\\\\d.\ 3\times10^{-2}=3\times0.01=0.03\leftarrow\huge\boxed{greater}\\\\e.\ 7\times10^{-5}=7\times0.00001=0.00007 \ \textless \ 0.0007\)
