Question

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

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

Answer 1

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 

Answer 2

Answer:

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