Factorize the following:

The greatest common factor of the terms $16 m$ and $4 m^{2}$ of the expression $16 m-4 m^{2}$ is $4 m$.

Also, we can write $16 m=4 m \times 4$ and $4 m^{2}=4 m \times m$.

$\therefore 16 m-4 m^{2}=4 m \times 4-4 m \times m$

$=4 m(4-m)$