Standard Form by Boxed Rockets

Are These Numbers in Standard Form?

6.86 \times 10^{-3}

Yes

0.987 \times 10^{-3}

No

73.9 \times 10^{6}

No

0.102 \times 10^{3}

No

3.39 \times 10^{-6}

Yes

26.9 \times 10^{-3}

No