The decimal expansion of \( 4\pi \) can be described as:
a non-terminating, non-repeating decimal
This is because \( \pi \) is an irrational number, meaning it cannot be expressed as a fraction and has a non-terminating, non-repeating decimal expansion. Thus, multiplying \( \pi \) by 4 will also result in a non-terminating, non-repeating decimal.