If a diameter of a circle (which is 18 inches) is tripled, can the expression 9 (254.34 in square) be used to find the new circle?

I know the answer is yes but I can't figure out how you work it! I come with 9(1,107.36 in square) but apparently that is not correct....
Would someone explain how they got this answer?
I have a quiz over it tomorrow.

Thank you

Daniel