how can i put 9 as an exponent?

You can just use ^ and your number you need after it to indicate you are using an exponent.

The x with the y as an exponent place key

Thanks guys you are both correct of course :))

If you want to enter 2⁹ you can

enter it as  2 [ x^y ] 9 = using the calc keys

or you you can type in 2^9 and press equals.

2^9 = 512