Standard Form by Boxed Rockets

Are These Numbers in Standard Form?

0.954 \times 10^{-4}

No

5.61 \times 10^{6}

Yes

7.41 \times 10^{-5}

Yes

2.5 \times 10^{5}

Yes

2.89 \times 10^{5}

Yes

0.452 \times 10^{4}

No