Standard Form by Boxed Rockets

Are These Numbers in Standard Form?

3.16 \times 10^{-4}

Yes

3.46 \times 10^{5}

Yes

0.706 \times 10^{-3}

No

8.09 \times 10^{-6}

Yes

43 \times 10^{-4}

No

7.67 \times 10^{-6}

Yes