Acube has side length a. the side lengths are decreased to 20% of their original size. write an expression in simplest form for the volume of the new cube in terms of a.

Volume of the original cube is a³ .
That's (a · a · a) .

If you decrease the sides to 20% of their original size,
then the new volume is  (0.2a · 0.2a × 0.2a).

That's  0.008a³  or  (0.2a)³ . 

Take your choice.  I can't decide which one is simpler.

I’m confused what’s happening