Answer :
[tex]1nm=1\times10^{-9}m[/tex]
We 0.3 of nanometers so let us multiply the above by 0.3 (both sides ).
[tex]0.3nm=0.3\times10^{-9}m[/tex]But here is the catch! now we have to make the above as a number multiplying exponent so.
[tex]0.3nm=0.3\times\frac{10}{10}\times10^{-9}m[/tex]We have simply divided and multiplied by 10/10 which is simply 1.
[tex]0.3nm=0.3\times10\times10^{-9}\times\frac{1}{10}m=3\times10^{-9}\times10^{-1}m=3\times10^{-10}m^{}[/tex]There it is, this is the answer.!