9*9 is just a broad way of saying 9 squared.
Or, 9^2.
9^2= 81
9*9= 81
An exponent is a number that makes a number seemingly less large- and can help you when you are using big numbers in math in the future. It would be easier to say 9^2- 9^3 then 9*9 - 9*9*9
I hope this helps!
~kaikers
