Standard Form by Boxed Rockets

Are These Numbers in Standard Form?

8.57 \times 10^{3}

Yes

0.855 \times 10^{4}

No

6.37 \times 10^{-6}

Yes

3.66 \times 10^{-5}

Yes

0.08 \times 10^{-6}

No

1.9 \times 10^{6}

Yes