How does adding the prefix mega- to a unit affect the quantity being described?

Explanation:

Mega as prefix to a unit affects the quantity substantially. Mega denotes a multiple of a million fold that is in ther order of 10⁶.

Other multiples used as prefixes to a unit are:

              hecto                               100

              kilo                                  1000

             mega                              1000000

When mega is added it shows a manifold of a million.

the answer is 75.0%.