What is a number that is not real?

Answer 1

i, which is *defined* as the square root of -1, is imaginary, not real.

The square root of -1 is i, the square root of -4 is 2i, the square root of -9 is 3i, etc.

i, 2i, 3i, 4i, 5i, etc. = non-real numbers.

'Real' numbers are all of the numbers in the world: integers, rational numbers, Irrational Numbers, positive, negative, etc.

Non-real (imaginary) numbers are numbers that exist only in theory such as the square root of a negative number, or the roots of an equation that never reaches the x-axis. (They are noted with the lowercase letter i for imaginary). This concept is very distant to most people outside of math classes.

Answer 2

The square root of -1 is not real.