We know that and .

Because 90 falls is approximately halfway between 81 and 100, the square root of 90 is approximately halfway between 9 and 10, or 9.5.

For percent problems there are verbal cues:

"IS" means equals and "OF" means multiplication.

Then the equation to solve becomes:

To place in order, first we must find a common denominator and convert all fractions to that denominator.

have a common denominator of .

have a common denominator of .

have a common denominator of .

Therefore we can use common denominators to make all of the fractions look similar. Then the ordering becomes trivial.

We are looking for a number that is not real.

, , and are irrational numbers, but they are still real.

Then, is equivalent to by the rules of complex numbers. Thus, it is also real.

That leaves us with: which in fact is imaginary (since no real number multiplied by itself yields a negative number) and simplifies to .

Real numbers can be found anywhere on a continuous number line ranging from negative infinity to positive infinity; therefore, all of the numbers are real numbers.