Inputing Scientific Numbers
If you mean using the "EE" key it's straightforward.
To enter scientific numbers, enter the number, then press EE, then the exponent value. The TI-30XA will stay in scientific display until you "clear" or turn it off. It will also switch to scientific notation if you multiply big numbers that exceed the display.
E.g. Input 3, EE, 10, X, 3, EE, 10, =, gives you the answer 9 times 10 to the power 20. Press the "square root" key and you will get back 3 times 10 to the power 10.
You can mix entries too, e.g. 3, EE, 10, X, 2, =, gives you 6 times 10 the power 10....