Simple math question

Hi all, I'm stuck on the calculations of a simple math problem. EK and wolfram alpha both have the same answer, I just don't get why it's correct.

The solution states that:
4(5.4*10^-3)^3 is about(=) 20*10^-9

However, it is to my understanding that the 5.4 should be cubed as well.. Can anyone clarify??

Simple math question