For a TI-30 calculator:
Take for example the number #1.52# x #10^5#. To type this number as it is in scientific notation, first type in 1.52. Next press the [2nd] key and then the key that has EE printed above it (it's the #x^"-1"# key). The EE means " x 10 to the power of". After you press the[EE] key, type in the exponent 5. The display should look like 1.52 with a 05 in the upper right portion of the display in smaller print, like this
**The TI-30XS MultiView™ scientific calculators do not have an [EE] key. Instead they have a shortcut key, [x10n] which can be used to enter exponents for scientific notation.
For a TI-83/84
To ensure that the number you type in remains in scientific notation, press the mode key and highlight SCI on the top line. If you keep it in NORMAL mode, the number will be expanded when you press the enter key.
Lets use the same example as the TI-30, #1.52# x #10^5#. Type in the 1.52. Next press the [2nd] key, then the key with the EE above it (it's the [ #,# ] "comma" key). Then type in the exponent. It will look like this: 1.52E05, which means #1.52# x #10^5#.
If you do not use a Texas Instrument calculator, you can probably find its manual or a set of instructions online.