Complex sentence: For multiplication, the version is probably not needed, but for division the negative power version probably is, for example, the ms-2 and m/s2 versions for m/s 2 and m ⋅ s − 2 styles.
Split into simpler sentences: For multiplication, the version is not preferred, but for division a negative power version is probably needed. For example, the ms-2 and m/s2 versions for m/s 2 and m ⋅ s − 2 styles.