Question

All of the numbers below are real numbers except which number?

-0.625
sq root (8)
sq root(16)
-0.625

Answer 1

The answer is √(-25), because this causes √(-25)=5i, which is an imaginary number, not a real number.

Answer 2

All of the numbers below are real numbers except which number?

answer is
sq root (-25)

P.S.
NOT a Real Number: imaginary Numbers or Infinity